Diving reflex

The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date.[1][2][3] It optimizes respiration by preferentially distributing oxygen stores to the heart and brain, enabling submersion for an extended time.

The diving reflex is exhibited strongly in aquatic mammals, such as seals,[1][4] otters, dolphins,[5] and muskrats,[6] and exists as a lesser response in other animals, including adult humans,[7] babies up to 6 months old (see infant swimming), and diving birds, such as ducks and penguins.[1]

The diving reflex is triggered specifically by chilling and wetting the nostrils and face while breath-holding,[2][8] and is sustained via neural processing originating in the carotid chemoreceptors. The most noticeable effects are on the cardiovascular system, which displays peripheral vasoconstriction, slowed heart rate, redirection of blood to the vital organs to conserve oxygen, release of red blood cells stored in the spleen, and, in humans, heart rhythm irregularities.[2] Although aquatic animals have evolved profound physiological adaptations to conserve oxygen during submersion, the apnea and its duration, bradycardia, vasoconstriction, and redistribution of cardiac output occur also in terrestrial animals as a neural response, but the effects are more profound in natural divers.[1][3]

## Contents

* 1 Physiological response
* 1.1 Carotid body chemoreceptors
* 1.2 Circulatory responses
* 1.2.1 Bradycardia and cardiac output
* 1.2.2 Splenic contraction
* 1.2.3 Blood shift
* 1.2.4 Arrhythmias
* 1.3 Renal and water balance responses
* 1.4 Respiratory responses
* 2 Adaptations of aquatic mammals
* 3 History
* 4 See also
* 5 References

## Physiological response[edit | edit source]

When the face is submerged and water fills the nostrils, sensory receptors sensitive to wetness within the nasal cavity and other areas of the face supplied by the fifth (V) cranial nerve (the trigeminal nerve) relay the information to the brain.[1] The tenth (X) cranial nerve, (the vagus nerve) - part of the autonomic nervous system - then produces bradycardia and other neural pathways elicit peripheral vasoconstriction, restricting blood from limbs and all organs to preserve blood and oxygen for the heart and the brain (and lungs), concentrating flow in a heart–brain circuit and allowing the animal to conserve oxygen.[3][6]

In humans, the diving reflex is not induced when limbs are introduced to cold water. Mild bradycardia is caused by subjects holding their breath without submerging the face in water.[9][10] When breathing with the face submerged, the diving response increases proportionally to decreasing water temperature.[8] However, the greatest bradycardia effect is induced when the subject is holding their breath with their face wetted.[9] Apnea with nostril and facial cooling are triggers of this reflex.[1][8]

The diving response in animals, such as the dolphin, varies considerably depending on level of exertion during foraging.[5] Children tend to survive longer than adults when deprived of oxygen underwater. The exact mechanism for this effect has been debated and may be a result of brain cooling similar to the protective effects seen in people treated with deep hypothermia.[10][11]

### Carotid body chemoreceptors[edit | edit source]

During sustained breath-holding while submerged, blood oxygen levels decline while carbon dioxide and acidity levels rise,[1] stimuli that collectively act upon chemoreceptors located in the bilateral carotid bodies.[12] As sensory organs, the carotid bodies convey the chemical status of the circulating blood to brain centers regulating neural outputs to the heart and circulation.[1][12] Preliminary evidence in ducks and humans indicates that the carotid bodies are essential for these integrated cardiovascular responses of the diving response,[12][13] establishing a "chemoreflex" characterized by parasympathetic (slowing) effects on the heart and sympathetic (vasoconstrictor) effects on the vascular system.[1][14]

### Circulatory responses[edit | edit source]

Plasma fluid losses due to immersion diuresis occur within a short period of immersion.[15] Head-out immersion causes a blood shift from the limbs and into the thorax. The fluid shift is largely from the extravascular tissues and the increased atrial volume results in a compensatory diuresis. Plasma volume, stroke volume, and cardiac output remain higher than normal during immersion. The increased respiratory and cardiac workload causes increased blood flow to the cardiac and respiratory muscles. Stroke volume is not greatly affected by immersion or variation in ambient pressure, but bradycardia reduces the overall cardiac output, particularly due to the diving reflex in breath-hold diving.[16]

#### Bradycardia and cardiac output[edit | edit source]

Bradycardia is the response to facial contact with cold water: the human heart rate slows down ten to twenty-five percent.[8] Seals experience changes that are even more dramatic, going from about 125 beats per minute to as low as 10 on an extended dive.[4][17] During breath-holding, humans also display reduced left ventricular contractility and diminished cardiac output,[9][18] effects that may be more severe during submersion due to hydrostatic pressure.[18]

Slowing the heart rate reduces the cardiac oxygen consumption, and compensates for the hypertension due to vasoconstriction. However, breath-hold time is reduced when the whole body is exposed to cold water as the metabolic rate increases to compensate for accelerated heat loss even when the heart rate is significantly slowed.[2]

#### Splenic contraction[edit | edit source]

The spleen contracts in response to lowered levels of oxygen and increased levels of carbon dioxide, releasing red blood cells and increasing the oxygen capacity of the blood.[19] This may start before the bradycardia.[2]

#### Blood shift[edit | edit source]

Blood shift has at least two separate meanings: In medicine, it is synonymous with left shift

Blood shift is a term used when blood flow to the extremities is redistributed to the head and torso during a breath-hold dive. Peripheral vasoconstriction occurs during submersion by resistance vessels limiting blood flow to muscles, skin, and viscera, regions which are "hypoxia-tolerant", thereby preserving oxygenated blood for the heart, lungs, and brain.[3] The increased resistance to peripheral blood flow raises the blood pressure, which is compensated by bradycardia, conditions which are accentuated by cold water.[2] Aquatic mammals have blood volume that is some three times larger per mass than in humans, a difference augmented by considerably more oxygen bound to hemoglobin and myoglobin of diving mammals, enabling prolongation of submersion after capillary blood flow in peripheral organs is minimized.[2]

#### Arrhythmias[edit | edit source]

Cardiac arrhythmias are a common characteristic of the human diving response.[2][20] As part of the diving reflex, increased activity of the cardiac parasympathetic nervous system not only regulates the bradycardia, but also is associated with ectopic beats which are characteristic of human heart function during breath-hold dives.[2] Arrhythmias may be accentuated by neural responses to face immersion in cold water, distension of the heart due to central blood shift, and the increasing resistance to left ventricular ejection (afterload) by rising blood pressure.[2] Other changes commonly measured in the electrocardiogram during human breath-hold dives include ST depression, heightened T wave, and a positive U wave following the QRS complex,[2] measurements associated with reduced left ventricular contractility and overall depressed cardiac function during a dive.[9][18]

### Renal and water balance responses[edit | edit source]

In hydrated subjects immersion will cause diuresis and excretion of sodium and potassium. Diuresis is reduced in dehydrated subjects, and in trained athletes in comparison with sedentary subjects.[16]

### Respiratory responses[edit | edit source]

Snorkel breathing is limited to shallow depths just below the surface due to the effort required during inhalation to overcome the hydrostatic pressure on the chest.[16] Hydrostatic pressure on the surface of the body due to head-out immersion in water causes negative pressure breathing which shifts blood into the intrathoracic circulation.[15]

Lung volume decreases in the upright position due to cranial displacement of the abdomen due to hydrostatic pressure, and resistance to air flow in the airways increases significantly because of the decrease in lung volume.[15]

Hydrostatic pressure differences between the interior of the lung and the breathing gas delivery, increased breathing gas density due to ambient pressure, and increased flow resistance due to higher breathing rates may all cause increased work of breathing and fatigue of the respiratory muscles.[16]

There appears to be a connection between pulmonary edema and increased pulmonary blood flow and pressure which results in capillary engorgement. This may occur during higher intensity exercise while immersed or submersed.[16]

Facial immersion at the time of initiating breath-hold is a necessary factor for maximising the mammalian diving reflex in humans.[21]

## Adaptations of aquatic mammals[edit | edit source]

Further information: Physiology of underwater diving § Marine mammals

Diving mammals have an elastic aortic bulb thought to help maintain arterial pressure during the extended intervals between heartbeats during dives, and have high blood volume, combined with large storage capacity in veins and retes of the thorax and head in seals and dolphins.[3] Chronic physiological adaptations of blood include elevated hematocrit, hemoglobin, and myoglobin levels which enable greater oxygen storage and delivery to essential organs during a dive.[3] Oxygen use is minimised during the diving reflex by energy efficient swimming or gliding behaviour, and regulation of metabolism, heart rate, and peripheral vasoconstriction.[3]

Aerobic diving capacity is limited by available oxygen and the rate at which it is consumed. Diving mammals and birds have a considerably greater blood volume than terrestrial animals of similar size, and in addition have a far greater concentration of haemoglobin and myoglobin, and this haemoglobin and myoglobin is also capable of carrying a higher oxygen load. During diving, the hematocrit and hemoglobin are temporarily increased by reflex splenic contraction, which discharges a large additional amount of red blood cells. The brain tissue of diving mammals also contains higher levels of neuroglobin and cytoglobin than terrestrial animals.[3]

Aquatic mammals seldom dive beyond their aerobic diving limit, which is related to the myoglobin oxygen stored. The muscle mass of aquatic mammals is relatively large, so the high myoglobin content of their skeletal muscles provides a large reserve. Myoglobin-bound oxygen is only released in relatively hypoxic muscle tissue, so the peripheral vasoconstriction due to the diving reflex makes the muscles ischaemic and promotes early use of myoglobin bound oxygen.[3]

## History[edit | edit source]

The diving bradycardia was first described by Edmund Goodwyn in 1786 and later by Paul Bert in 1870.[22]

## See also[edit | edit source]

* Blood shift - Set index article - Set index article
* Cold shock response - Physiological response to sudden exposure to cold - Physiological response to sudden exposure to cold
* Bradycardia - Heart rate that is below the normal range - Heart rate that is below the normal range

## References[edit | edit source]

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Butler, P. J; Jones, D. R (1997). "Physiology of diving of birds and mammals" (PDF). Physiological Reviews. 77 (3): 837–99. doi:10.1152/physrev.1997.77.3.837. PMID 9234967. Archived (PDF) from the original on 2017-08-09. Retrieved 2018-04-22.
2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Lindholm, Peter; Lundgren, Claes EG (1 January 2009). "The physiology and pathophysiology of human breath-hold diving". Journal of Applied Physiology. 106 (1): 284–292. doi:10.1152/japplphysiol.90991.2008. PMID 18974367. S2CID 6379788.
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Michael Panneton, W (2013). "The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life?". Physiology. 28 (5): 284–297. doi:10.1152/physiol.00020.2013. PMC 3768097. PMID 23997188.
4. ↑ 4.0 4.1 Zapol WM, Hill RD, Qvist J, Falke K, Schneider RC, Liggins GC, Hochachka PW (September 1989). "Arterial gas tensions and hemoglobin concentrations of the freely diving Weddell seal". Undersea Biomed Res. 16 (5): 363–73. PMID 2800051. Archived from the original on 2008-12-11. Retrieved 2008-06-14.
5. ↑ 5.0 5.1 Noren, S. R; Kendall, T; Cuccurullo, V; Williams, T. M (2012). "The dive response redefined: Underwater behavior influences cardiac variability in freely diving dolphins". Journal of Experimental Biology. 215 (Pt 16): 2735–41. doi:10.1242/jeb.069583. PMID 22837445.
6. ↑ 6.0 6.1 McCulloch, P. F. (2012). "Animal Models for Investigating the Central Control of the Mammalian Diving Response". Frontiers in Physiology. 3: 169. doi:10.3389/fphys.2012.00169. PMC 3362090. PMID 22661956.
7. ↑ Ilardo, Melissa A.; Moltke, Ida; Korneliussen, Thorfinn S.; Cheng, Jade; Stern, Aaron J.; Racimo, Fernando; de Barros Damgaard, Peter; Sikora, Martin; Seguin-Orlando, Andaine (April 2018). "Physiological and Genetic Adaptations to Diving in Sea Nomads". Cell. 173 (3): 569–580.e15. doi:10.1016/j.cell.2018.03.054. PMID 29677510.
8. ↑ 8.0 8.1 8.2 8.3 Speck DF, Bruce DS (March 1978). "Effects of varying thermal and apneic conditions on the human diving reflex". Undersea Biomed Res. 5 (1): 9–14. PMID 636078. Archived from the original on 2010-02-27. Retrieved 2008-06-14.
9. ↑ 9.0 9.1 9.2 9.3 Gross, P. M.; Terjung, R. L.; Lohman, T. G. (1976). "Left-ventricular performance in man during breath-holding and simulated diving". Undersea Biomedical Research. 3 (4): 351–60. PMID 10897861.
10. ↑ 10.0 10.1 Lundgren, Claus EG; Ferrigno, Massimo (eds). (1985). "Physiology of Breath-hold Diving. 31st Undersea and Hyperbaric Medical Society Workshop". UHMS Publication Number 72(WS-BH)4-15-87. Undersea and Hyperbaric Medical Society. Archived from the original on 2009-06-02. Retrieved 2009-04-16. `{{cite journal}}`: Cite journal requires `|journal=` (help)CS1 maint: multiple names: authors list (link)
11. ↑ Mackensen GB, McDonagh DL, Warner DS (March 2009). "Perioperative hypothermia: use and therapeutic implications". J. Neurotrauma. 26 (3): 342–58. doi:10.1089/neu.2008.0596. PMID 19231924.
12. ↑ 12.0 12.1 12.2 Butler, P. J; Stephenson, R (1988). "Chemoreceptor control of heart rate and behaviour during diving in the tufted duck (Aythya fuligula)". The Journal of Physiology. 397: 63–80. doi:10.1113/jphysiol.1988.sp016988. PMC 1192112. PMID 3137333.
13. ↑ Gross, P. M; Whipp, B. J; Davidson, J. T; Koyal, S. N; Wasserman, K (1976). "Role of the carotid bodies in the heart rate response to breath holding in man". Journal of Applied Physiology. 41 (3): 336–40. doi:10.1152/jappl.1976.41.3.336. PMID 965302.
14. ↑ Heusser, K; Dzamonja, G; Tank, J; Palada, I; Valic, Z; Bakovic, D; Obad, A; Ivancev, V; Breskovic, T; Diedrich, A; Joyner, M. J; Luft, F. C; Jordan, J; Dujic, Z (2009). "Cardiovascular regulation during apnea in elite divers". Hypertension. 53 (4): 719–24. doi:10.1161/HYPERTENSIONAHA.108.127530. PMID 19255361.
15. ↑ 15.0 15.1 15.2 Kollias, James; Van Derveer, Dena; Dorchak, Karen J.; Greenleaf, John E. (February 1976). "Physiologic responses to water immersion in man: A compendium of research" (PDF). Nasa Technical Memorandum X-3308. Washington, DC: National Aeronautics And Space Administration. Archived (PDF) from the original on 7 March 2017. Retrieved 12 October 2016.
16. ↑ 16.0 16.1 16.2 16.3 16.4 Pendergast, D. R.; Lundgren, C. E. G. (1 January 2009). "The underwater environment: cardiopulmonary, thermal, and energetic demands". Journal of Applied Physiology. 106 (1): 276–283. doi:10.1152/japplphysiol.90984.2008. ISSN 1522-1601. PMID 19036887. S2CID 2600072.
17. ↑ Thornton SJ, Hochachka PW (2004). "Oxygen and the diving seal". Undersea Hyperb Med. 31 (1): 81–95. PMID 15233163. Archived from the original on 2008-12-11. Retrieved 2008-06-14.
18. ↑ 18.0 18.1 18.2 Marabotti, C; Scalzini, A; Cialoni, D; Passera, M; l'Abbate, A; Bedini, R (2009). "Cardiac changes induced by immersion and breath-hold diving in humans". Journal of Applied Physiology. 106 (1): 293–7. doi:10.1152/japplphysiol.00126.2008. PMID 18467547.
19. ↑ Baković, D.; Eterović, D; Saratlija-Novaković, Z; Palada, I; Valic, Z.; Bilopavlović, N.; Dujić, Z. (November 2005). "Effect of human splenic contraction on variation in circulating blood cell counts". Clinical and Experimental Pharmacology and Physiology. 32 (11): 944–51. doi:10.1111/j.1440-1681.2005.04289.x. PMID 16405451.
20. ↑ Alboni, P; Alboni, M; Gianfranchi, L (2011). "Diving bradycardia: A mechanism of defence against hypoxic damage". Journal of Cardiovascular Medicine. 12 (6): 422–7. doi:10.2459/JCM.0b013e328344bcdc. PMID 21330930.
21. ↑ Campbell, L.B.; Gooden, B.A.; Horowitz, J.D. (1969). "Cardiovascular responses to partial and total immersion in man". Journal of Physiology. 202 (1): 239–250. doi:10.1113/jphysiol.1969.sp008807. PMC 1351477. PMID 5770894.
22. ↑ Vega, Jose L. (2017-08-01). "Edmund Goodwyn and the first description of diving bradycardia". Journal of Applied Physiology. 123 (2): 275–277. doi:10.1152/japplphysiol.00221.2017. ISSN 1522-1601. PMID 28495845.

* v
* t
* e

Reflexes

Cranial nerve|

* Pupillary light reflex
* Accommodation reflex
* Jaw jerk reflex
* Corneal reflex
* Caloric reflex test/Vestibulo-ocular reflex/Oculocephalic reflex
* Pharyngeal (gag) reflex

Stretch reflexes|

* Arm
* Biceps reflex
* Brachioradialis reflex
* Triceps reflex
* Leg
* Patellar reflex
* Ankle jerk reflex
* Plantar reflex

Primitive reflexes|

* Galant
* Gastrocolic
* Grasp
* Moro
* Rooting
* Stepping
* Sucking
* Tonic neck
* Parachute

Superficial reflexes|

* Abdominal reflex
* Cremasteric reflex

Cardiovascular|

* Bainbridge reflex
* Bezold–Jarisch reflex
* Coronary reflex
* Cushing reflex
* Diving reflex
* Oculocardiac reflex
* Baroreflex
* Reflex bradycardia
* Reflex tachycardia
* Respiratory
* Churchill–Cope reflex

Other|

* List of reflexes
* Acoustic reflex
* H-reflex
* Golgi tendon reflex
* Optokinetic
* Startle response
* Withdrawal reflex
* Crossed extensor reflex
* Symmetrical tonic neck reflex

* v
* t
* e

Underwater diving

* Diving modes
* Atmospheric pressure diving
* Freediving
* Saturation diving
* Scuba diving
* Snorkeling
* Surface oriented diving
* Surface-supplied diving
* Unmanned diving

Diving equipment

* Cleaning and disinfection of personal diving equipment
* Human factors in diving equipment design

| Basic equipment|

* Diving mask
* Snorkel
* Swimfin

|

Breathing gas|

* Bailout gas
* Bottom gas
* Breathing air
* Decompression gas
* Emergency gas supply
* Heliox
* Nitrox
* Oxygen
* Travel gas
* Trimix

Buoyancy and
trim equipment|

* Buoyancy compensator
* Power inflator
* Dump valve
* Diving weighting system
* Ankle weights
* Integrated weights
* Trim weights
* Weight belt

Decompression
equipment|

* Decompression buoy
* Decompression cylinder
* Decompression trapeze
* Dive computer
* Diving shot
* Jersey upline
* Jonline

Diving suit|

* Atmospheric diving suit
* Dry suit
* Sladen suit
* Standard diving suit
* Rash vest
* Wetsuit
* Dive skins
* Hot-water suit

Helmets
and masks|

* Anti-fog
* Diving helmet
* Free-flow helmet
* Lightweight demand helmet
* Orinasal mask
* Reclaim helmet
* Shallow water helmet
* Standard diving helmet
* Diving mask
* Band mask
* Full-face mask
* Half mask

Instrumentation|

* Bottom timer
* Depth gauge
* Dive computer
* Dive timer
* Diving watch
* Helium release valve
* Pneumofathometer
* Submersible pressure gauge

Mobility
equipment|

* Diving bell
* Closed bell
* Wet bell
* Diving stage
* Swimfin
* Monofin
* PowerSwim
* Towboard

| Diver
propulsion
vehicle|

* Advanced SEAL Delivery System
* Cosmos CE2F series
* Dry Combat Submersible
* Human torpedo
* Motorised Submersible Canoe
* Necker Nymph
* R-2 Mala-class swimmer delivery vehicle
* SEAL Delivery Vehicle
* Shallow Water Combat Submersible
* Siluro San Bartolomeo
* Wet Nellie
* Wet sub

|

Safety
equipment|

* Alternative air source
* Octopus regulator
* Pony bottle
* Bolt snap
* Buddy line
* Dive light
* Diver's cutting tool
* Diver's knife
* Diver's telephone
* Through-water communications
* Diving bell
* Diving safety harness
* Emergency gas supply
* Bailout block
* Bailout bottle
* Lifeline
* Screw gate carabiner
* Emergency locator beacon
* Rescue tether
* Safety helmet
* Shark-proof cage
* Snoopy loop
* Navigation equipment
* Distance line
* Diving compass
* Dive reel
* Line marker
* Surface marker buoy
* Silt screw

Underwater
breathing
apparatus|

* Atmospheric diving suit
* Diving cylinder
* Burst disc
* Diving cylinder valve
* Diving helmet
* Reclaim helmet
* Diving regulator
* Mechanism of diving regulators
* Regulator malfunction
* Regulator freeze
* Single-hose regulator
* Twin-hose regulator
* Full face diving mask

| Open-circuit
scuba|

* Scuba set
* Bailout bottle
* Decompression cylinder
* Independent doubles
* Manifolded twin set
* Scuba manifold
* Pony bottle
* Scuba configuration
* Sidemount
* Sling cylinder

|

Diving
rebreathers|

* Carbon dioxide scrubber
* Carleton CDBA
* CDLSE
* Cryogenic rebreather
* CUMA
* DSEA
* Dolphin
* Electro-galvanic oxygen sensor
* FROGS
* Halcyon PVR-BASC
* Halcyon RB80
* IDA71
* Interspiro DCSC
* KISS
* LAR-5
* LAR-6
* LAR-V
* LARU
* Porpoise
* Ray
* Siebe Gorman CDBA
* Siva
* Viper

Surface-supplied
diving equipment|

* Air line
* Diver's umbilical
* Diving air compressor
* Gas panel
* Hookah
* Scuba replacement
* Sea Trek
* Snuba
* Standard diving dress

Escape set|

* Davis Submerged Escape Apparatus
* Momsen lung
* Steinke hood
* Submarine Escape Immersion Equipment

Diving
equipment
manufacturers|

* AP Diving
* Apeks
* Aqua Lung America
* Aqua Lung/La Spirotechnique
* Beuchat
* René Cavalero
* Cis-Lunar
* Cressi-Sub
* Dacor
* DESCO
* Dive Xtras
* Divex
* Diving Unlimited International
* Drägerwerk
* Fenzy
* Maurice Fernez
* Technisub
* Oscar Gugen
* Heinke
* HeinrichsWeikamp
* Johnson Outdoors
* Mares
* Morse Diving
* Nemrod
* Oceanic Worldwide
* Porpoise
* Sub Sea Systems
* Shearwater Research
* Siebe Gorman
* Submarine Products
* Suunto

Diving support equipment

| Access equipment|

* Boarding stirrup
* Diver lift
* Diving bell
* Diving ladder
* Diving platform (scuba)
* Diving stage
* Downline
* Jackstay
* Launch and recovery system
* Messenger line
* Moon pool

|

Breathing gas
handling|

* Air filtration
* Activated carbon
* Hopcalite
* Molecular sieve
* Silica gel
* Booster pump
* Carbon dioxide scrubber
* Cascade filling system
* Diver's pump
* Diving air compressor
* Diving air filter
* Water separator
* High pressure breathing air compressor
* Low pressure breathing air compressor
* Gas blending
* Gas blending for scuba diving
* Gas panel
* Gas reclaim system
* Gas storage bank
* Gas storage quad
* Gas storage tube
* Helium analyzer
* Nitrox production
* Membrane gas separation
* Pressure swing adsorption
* Oxygen analyser
* Oxygen compatibility

Decompression
equipment|

* Built-in breathing system
* Decompression tables
* Diving bell
* Bell cursor
* Closed bell
* Clump weight
* Launch and recovery system
* Wet bell
* Diving chamber
* Diving stage
* Recreational Dive Planner
* Saturation system

Platforms|

* Dive boat
* Canoe and kayak diving
* Combat Rubber Raiding Craft
* Liveaboard
* Subskimmer
* Diving support vessel
* HMS Challenger (K07)

| Underwater
habitat|

* Aquarius Reef Base
* Continental Shelf Station Two
* Helgoland Habitat
* Jules' Undersea Lodge
* Scott Carpenter Space Analog Station
* SEALAB
* Tektite habitat

|

Remotely operated
underwater vehicles|

* 8A4-class ROUV
* ABISMO
* Atlantis ROV Team
* CURV
* Deep Drone
* Épaulard
* Global Explorer ROV
* Goldfish-class ROUV
* Kaikō ROV
* Kaşif ROUV
* Long-Term Mine Reconnaissance System
* Mini Rover ROV
* OpenROV
* ROV KIEL 6000
* ROV PHOCA
* Scorpio ROV
* Sea Dragon-class ROV
* Seabed tractor
* Seafox drone
* Seahorse ROUV
* SeaPerch
* SJT-class ROUV
* T1200 Trenching Unit
* VideoRay UROVs

Safety equipment|

* Diver down flag
* Diving shot
* Hyperbaric lifeboat
* Hyperbaric stretcher
* Jackstay
* Jonline
* Reserve gas supply

General|

* Diving spread
* Air spread
* Saturation spread
* Hot water system
* Sonar
* Underwater acoustic positioning system
* Underwater acoustic communication

Freediving

| Activities|

* Aquathlon
* Apnoea finswimming
* Freediving
* Haenyeo
* Pearl hunting
* Ama
* Snorkeling
* Spearfishing
* Underwater football
* Underwater hockey
* Underwater ice hockey
* Underwater rugby
* Underwater target shooting

|

Competitions|

* Nordic Deep
* Vertical Blue
* Disciplines
* Constant weight (CWT)
* Constant weight without fins (CNF)
* Dynamic apnea (DYN)
* Dynamic apnea without fins (DNF)
* Free immersion (FIM)
* No-limits apnea (NLT)
* Static apnea (STA)
* Skandalopetra diving
* Variable weight apnea (VWT)
* Variable weight apnea without fins

Equipment|

* Diving mask
* Diving suit
* Hawaiian sling
* Polespear
* Snorkel (swimming)
* Speargun
* Swimfins
* Monofin
* Water polo cap

Freedivers|

* Deborah Andollo
* Peppo Biscarini
* Sara Campbell
* Derya Can Göçen
* Goran Čolak
* Carlos Coste
* Robert Croft
* Mandy-Rae Cruickshank
* Yasemin Dalkılıç
* Leonardo D'Imporzano
* Flavia Eberhard
* Şahika Ercümen
* Emma Farrell
* Francisco Ferreras
* Pierre Frolla
* Flavia Eberhard
* Mehgan Heaney-Grier
* Elisabeth Kristoffersen
* Loïc Leferme
* Enzo Maiorca
* Jacques Mayol
* Audrey Mestre
* Karol Meyer
* Stéphane Mifsud
* Alexey Molchanov
* Natalia Molchanova
* Dave Mullins
* Patrick Musimu
* Guillaume Néry
* Herbert Nitsch
* Umberto Pelizzari
* Annelie Pompe
* Michal Risian
* Stig Severinsen
* Tom Sietas
* Aharon Solomons
* Martin Štěpánek
* Walter Steyn
* Tanya Streeter
* William Trubridge
* Devrim Cenk Ulusoy
* Danai Varveri
* Alessia Zecchini
* Nataliia Zharkova

Hazards|

* Barotrauma
* Drowning
* Freediving blackout
* Deep-water blackout
* Shallow-water blackout
* Hypercapnia
* Hypothermia

Historical|

* Ama
* Octopus wrestling
* Swimming at the 1900 Summer Olympics – Men's underwater swimming

Organisations|

* AIDA International
* Scuba Schools International
* Australian Underwater Federation
* British Freediving Association
* Confédération Mondiale des Activités Subaquatiques
* Fédération Française d'Études et de Sports Sous-Marins
* Performance Freediving International

Professional diving

| Occupations|

* Ama
* Commercial diver
* Commercial offshore diver
* Hazmat diver
* Divemaster
* Diving instructor
* Diving safety officer
* Diving superintendent
* Diving supervisor
* Haenyeo
* Media diver
* Police diver
* Public safety diver
* Scientific diver
* Underwater archaeologist

| Military diving|

* Army engineer diver
* Clearance diver
* Frogman
* List of military diving units
* Royal Navy ships diver
* Special Boat Service
* United States military divers
* U.S. Navy diver
* U.S.Navy master diver
* United States Navy SEALs
* Underwater Demolition Team

|

Underwater work|

* Commercial offshore diving
* Dive leader
* Diver training
* Recreational diver training
* Hyperbaric welding
* Media diving
* Nondestructive testing
* Pearl hunting
* Police diving
* Potable water diving
* Public safety diving
* Scientific diving
* Ships husbandry
* Sponge diving
* Submarine pipeline
* Underwater archaeology
* Archaeology of shipwrecks
* Underwater construction
* Offshore construction
* Underwater demolition
* Underwater photography
* Underwater search and recovery
* Underwater videography

| Salvage diving|

* SS Egypt
* Kronan
* La Belle
* SS Laurentic
* RMS Lusitania
* Mars
* Mary Rose
* USS Monitor
* HMS Royal George
* Vasa

|

Diving contractors|

* COMEX
* Helix Energy Solutions Group

Tools & equipment|

* Abrasive waterjet
* Airlift
* Baited remote underwater video
* In-water surface cleaning
* Brush cart
* Cavitation cleaning
* Pressure washing
* Pigging
* Lifting bag
* Remotely operated underwater vehicle
* Thermal lance
* Tremie
* Water jetting

Underwater
weapons|

* Limpet mine
* Speargun
* Hawaiian sling
* Polespear

| Underwater
firearm|

* Gyrojet
* Mk 1 Underwater Defense Gun
* Powerhead
* Underwater pistols
* Heckler & Koch P11
* SPP-1 underwater pistol
* Underwater revolvers
* AAI underwater revolver
* Underwater rifles
* ADS amphibious rifle
* APS underwater rifle
* ASM-DT amphibious rifle

|

Recreational diving

| Specialties|

* Altitude diving
* Cave diving
* Deep diving
* Ice diving
* Muck diving
* Open-water diving
* Rebreather diving
* Sidemount diving
* Solo diving
* Technical diving
* Underwater photography
* Wreck diving

|

Diver
organisations|

* British Sub-Aqua Club (BSAC)
* Cave Divers Association of Australia (CDAA)
* Cave Diving Group (CDG)
* Comhairle Fo-Thuinn (CFT)
* Confédération Mondiale des Activités Subaquatiques (CMAS)
* Federación Española de Actividades Subacuáticas (FEDAS)
* Fédération Française d'Études et de Sports Sous-Marins (FFESSM)
* International Association for Handicapped Divers (IAHD)
* National Association for Cave Diving (NACD)
* Woodville Karst Plain Project (WKPP)

Diving tourism
industry|

* Dive center
* Environmental impact of recreational diving
* Scuba diving tourism
* Shark tourism
* Sinking ships for wreck diving sites

Diving events
and festivals|

* Diversnight
* Underwater Bike Race

Recreational
dive sites|

| Reef diving
regions|

* Aliwal Shoal Marine Protected Area
* Arrecifes de Cozumel National Park
* Edmonds Underwater Park
* Great Barrier Reef
* iSimangaliso Marine Protected Area
* Poor Knights Islands
* Table Mountain National Park Marine Protected Area

|

Reef dive
sites|

* Artificial reef
* Gibraltar Artificial Reef
* Shark River Reef
* Osborne Reef
* Fanadir
* Gamul Kebir
* Palancar Reef
* Underwater artworks
* Cancún Underwater Museum
* Christ of the Abyss
* Molinere Underwater Sculpture Park

Wreck diving
regions|

* Chuuk Lagoon
* Edmonds Underwater Park
* Finger Lakes Underwater Preserve Association
* Maritime Heritage Trail – Battle of Saipan
* Michigan Underwater Preserves
* Robben Island Marine Protected Area
* Table Mountain National Park Marine Protected Area
* Tulagi
* Tulamben
* Whitefish Point Underwater Preserve
* Wreck Alley, San Diego

Wreck dive
sites|

* HMS A1
* HMS A3
* USS Aaron Ward
* Abessinia
* Aeolian Sky
* Albert C. Field
* Andrea Doria
* Antilla
* Antilles
* Aquila
* USS Arkansas
* Bianca C.
* SS Binnendijk
* HMS Boadicea
* Booya
* HMSAS Bloemfontein
* Breda
* HMAS Brisbane
* HMHS Britannic
* Bungsberg
* HMAS Canberra
* Carl D. Bradley
* Carnatic
* SMS Dresden
* Dunraven
* Eastfield
* HMT Elk
* Ellengowan
* RMS Empress of Ireland
* HMS Falmouth
* Fifi
* SS Francisco Morazan
* Fujikawa Maru
* Fumizuki
* SATS General Botha
* USNS General Hoyt S. Vandenberg
* HMS Ghurka
* Glen Strathallan
* SAS Good Hope
* Gothenburg
* Herzogin Cecilie
* Hilma Hooker
* Hispania
* HMS Hood
* HMAS Hobart
* Igara
* James Eagan Layne
* Captain Keith Tibbetts
* King Cruiser
* SMS Kronprinz
* Kyarra
* HMS Laforey
* USAT Liberty
* Louis Sheid
* USS LST-507
* SMS Markgraf
* Mikhail Lermontov
* HMS M2
* Maine
* Maloja
* HMS Maori
* Marguerite
* SS Mauna Loa
* USAT Meigs
* Mendi
* USCGC Mohawk
* Mohegan
* RMS Moldavia
* HMS Montagu
* MV RMS Mulheim
* Nagato
* Oceana
* USS Oriskany
* Oslofjord
* P29
* P31
* Pedernales
* Persier
* HMAS Perth
* SAS Pietermaritzburg
* Piłsudski
* Pool Fisher
* HMS Port Napier
* Preußen
* President Coolidge
* PS Queen Victoria
* Radaas
* Rainbow Warrior
* RMS Rhone
* Rondo
* Rosehill
* Rotorua
* Royal Adelaide
* Royal Charter
* Rozi
* HMS Safari
* Salem Express
* USS Saratoga
* USS Scuffle
* HMS Scylla
* HMS Sidon
* USS Spiegel Grove
* Stanegarth
* Stanwood
* Stella
* HMAS Swan
* USS Tarpon
* Thesis
* Thistlegorm
* Toa Maru
* Torrey Canyon
* SAS Transvaal
* U-40
* U-352
* U-1195
* Um El Faroud
* Varvassi
* Walter L M Russ
* Washingtonian (1913)
* HMNZS Wellington
* USS Yancey
* Yongala
* Zenobia
* Zealandia
* Zingara

Cave diving
sites|

* Blauhöhle
* Chinhoyi Caves
* Devil's Throat at Punta Sur
* Engelbrecht Cave
* Fossil Cave
* Jordbrugrotta
* Piccaninnie Ponds
* Pluragrotta
* Pollatoomary
* Sistema Ox Bel Ha
* Sistema Sac Actun
* Sistema Dos Ojos
* Sistema Nohoch Nah Chich

Freshwater
dives|

* Dutch Springs
* Ewens Ponds
* Little Blue Lake

Training sites|

* Capernwray Dive Centre
* Deepspot
* National Diving and Activity Centre
* Stoney Cove

Open ocean
diving|

* Blue-water diving
* Black-water diving

Diving safety

* Human factors in diving equipment design
* Human factors in diving safety
* Life-support system
* Safety-critical system
* Scuba diving fatalities

| Diving
hazards|

* List of diving hazards and precautions
* Environmental
* Current
* Delta-P
* Entanglement hazard
* Overhead
* Silt out
* Wave action
* Equipment
* Freeflow
* Use of breathing equipment in an underwater environment
* Failure of diving equipment other than breathing apparatus
* Single point of failure
* Physiological
* Cold shock response
* Decompression
* Nitrogen narcosis
* Oxygen toxicity
* Seasickness
* Uncontrolled decompression
* Diver behaviour and competence
* Lack of competence
* Overconfidence effect
* Panic
* Task loading
* Trait anxiety
* Willful violation

| Consequences|

* Barotrauma
* Decompression sickness
* Drowning
* Hypothermia
* Hypoxia
* Hypercapnia
* Hyperthermia

|

Diving
procedures|

* Ascending and descending
* Emergency ascent
* Boat diving
* Canoe and kayak diving
* Buddy diving
* buddy check
* Decompression
* Decompression practice
* Pyle stop
* Ratio decompression
* Dive briefing
* Dive log
* Dive planning
* Scuba gas planning
* Diver communications
* Diving hand signals
* Diving line signals
* Diver voice communications
* Diver rescue
* Diver training
* Doing It Right
* Drift diving
* Gas blending for scuba diving
* Night diving
* Solo diving
* Water safety

Risk
management|

* Checklist
* Hazard identification and risk assessment
* Hazard analysis
* Job safety analysis
* Risk assessment
* Risk control
* Hierarchy of hazard controls
* Incident pit
* Lockout–tagout
* Permit To Work
* Redundancy
* Safety data sheet
* Situation awareness

| Diving team|

* Bellman
* Chamber operator
* Diver medical technician
* Diver's attendant
* Diving supervisor
* Diving systems technician
* Gas man
* Life support technician
* Stand-by diver

|

Equipment
safety|

* Breathing gas quality
* Testing and inspection of diving cylinders
* Hydrostatic test
* Sustained load cracking
* Diving regulator
* Breathing performance of regulators

Occupational
safety and
health|

* Approaches to safety
* Job safety analysis
* Risk assessment
* Toolbox talk
* Housekeeping
* Association of Diving Contractors International
* Code of practice
* Contingency plan
* Diving regulations
* Emergency procedure
* Emergency response plan
* Evacuation plan
* Hazardous Materials Identification System
* Hierarchy of hazard controls
* Administrative controls
* Engineering controls
* Hazard elimination
* Hazard substitution
* Personal protective equipment
* International Marine Contractors Association
* Occupational hazard
* Biological hazard
* Chemical hazard
* Physical hazard
* Psychosocial hazard
* Occupational hygiene
* Exposure assessment
* Occupational exposure limit
* Workplace health surveillance
* Safety culture
* Code of practice
* Diving safety officer
* Diving superintendent
* Health and safety representative
* Operations manual
* Safety meeting
* Standard operating procedure

Diving medicine

| Diving
disorders|

* List of signs and symptoms of diving disorders
* Cramp
* Motion sickness
* Surfer's ear

| Pressure
related|

* Alternobaric vertigo
* Barostriction
* Barotrauma
* Air embolism
* Aerosinusitis
* Barodontalgia
* Dental barotrauma
* Pulmonary barotrauma
* Compression arthralgia
* Decompression illness
* Dysbarism

| Oxygen|

* Freediving blackout
* Hyperoxia
* Hypoxia
* Oxygen toxicity

|

Inert gases|

* Avascular necrosis
* Decompression sickness
* Isobaric counterdiffusion
* Taravana
* Dysbaric osteonecrosis
* High-pressure nervous syndrome
* Hydrogen narcosis
* Nitrogen narcosis

Carbon dioxide|

* Hypercapnia
* Hypocapnia

Breathing gas
contaminants|

* Carbon monoxide poisoning

Immersion
related|

* Asphyxia
* Drowning
* Hypothermia
* Immersion diuresis
* Instinctive drowning response
* Laryngospasm
* Salt water aspiration syndrome
* Swimming-induced pulmonary edema

Treatment|

* Demand valve oxygen therapy
* First aid
* Hyperbaric medicine
* Hyperbaric treatment schedules
* In-water recompression
* Oxygen therapy
* Therapeutic recompression

Personnel|

* Diving Medical Examiner
* Diving Medical Practitioner
* Diving Medical Technician
* Hyperbaric nursing

Screening|

* Atrial septal defect
* Effects of drugs on fitness to dive
* Fitness to dive
* Psychological fitness to dive

Research|

| Researchers in
diving physiology
and medicine|

* Arthur J. Bachrach
* Albert R. Behnke
* Paul Bert
* George F. Bond
* Robert Boyle
* Albert A. Bühlmann
* John R. Clarke
* Guybon Chesney Castell Damant
* Kenneth William Donald
* William Paul Fife
* John Scott Haldane
* Robert William Hamilton Jr.
* Leonard Erskine Hill
* Brian Andrew Hills
* Felix Hoppe-Seyler
* Christian J. Lambertsen
* Simon Mitchell
* Charles Momsen
* John Rawlins R.N.
* Charles Wesley Shilling
* Edward D. Thalmann
* Jacques Triger

|

Diving medical
research
organisations|

* Aerospace Medical Association
* Divers Alert Network (DAN)
* Diving Diseases Research Centre (DDRC)
* Diving Medical Advisory Council (DMAC)
* European Diving Technology Committee (EDTC)
* European Underwater and Baromedical Society (EUBS)
* National Board of Diving and Hyperbaric Medical Technology
* Naval Submarine Medical Research Laboratory
* Royal Australian Navy School of Underwater Medicine
* Rubicon Foundation
* South Pacific Underwater Medicine Society (SPUMS)
* Southern African Underwater and Hyperbaric Medical Association (SAUHMA)
* Undersea and Hyperbaric Medical Society (UHMS)
* United States Navy Experimental Diving Unit (NEDU)

Law

* Civil liability in recreational diving
* Diving regulations
* Duty of care
* List of legislation regulating underwater diving
* Investigation of diving accidents
* UNESCO Convention on the Protection of the Underwater Cultural Heritage

History of underwater diving

* History of decompression research and development
* History of scuba diving
* List of researchers in underwater diving
* Timeline of diving technology
* Underwater diving in popular culture

| Archeological
sites|

* SS Commodore
* USS Monitor
* Queen Anne's Revenge
* Whydah Gally

|

Underwater art
and artists|

* The Diver
* Jason deCaires Taylor

Engineers
and inventors|

* William Beebe
* Georges Beuchat
* John R. Clarke
* Jacques Cousteau
* Charles Anthony Deane
* John Deane
* Ted Eldred
* Henry Fleuss
* Émile Gagnan
* Joseph-Martin Cabirol
* Christian J. Lambertsen
* Yves Le Prieur
* John Lethbridge
* Ernest William Moir
* Joseph Salim Peress
* Auguste Piccard
* Willard Franklyn Searle
* Augustus Siebe
* Jacques Triger

Equipment|

* Aqua-Lung
* RV Calypso
* SP-350 Denise
* Nikonos
* Porpoise regulator
* Standard diving dress
* Vintage scuba

Military and
covert operations|

* Raid on Alexandria (1941)
* Sinking of the Rainbow Warrior

Scientific projects|

* 1992 cageless shark-diving expedition
* Mission 31

Incidents|

| Dive boat incidents|

* Sinking of MV Conception
* Fire on MV Red Sea Aggressor

|

Diver rescues|

* Alpazat cave rescue
* Tham Luang cave rescue

Early diving|

* John Day (carpenter)
* Charles Spalding
* Ebenezer Watson

Freediving fatalities|

* Loïc Leferme
* Audrey Mestre
* Nicholas Mevoli
* Natalia Molchanova

Offshore
diving incidents|

* Byford Dolphin diving bell accident
* Drill Master diving accident
* Star Canopus diving accident
* Stena Seaspread diving accident
* Venture One diving accident
* Waage Drill II diving accident
* Wildrake diving accident

Professional
diving fatalities|

* Roger Baldwin
* John Bennett
* Victor F. Guiel Jr.
* Craig M. Hoffman
* Peter Henry Michael Holmes
* Johnson Sea Link accident
* Edwin Clayton Link
* Gerard Anthony Prangley
* Pier Skipness
* Robert John Smyth
* Albert D. Stover
* Richard A. Walker
* Lothar Michael Ward
* Joachim Wendler
* Bradley Westell
* Arne Zetterström

Scuba diving
fatalities|

* Ricardo Armbruster
* Allan Bridge
* David Bright
* Berry L. Cannon
* Cotton Coulson
* Cláudio Coutinho
* E. Yale Dawson
* Deon Dreyer
* Milan Dufek
* Sheck Exley
* Maurice Fargues
* Fernando Garfella Palmer
* Guy Garman
* Steve Irwin
* Jim Jones
* Henry Way Kendall
* Artur Kozłowski
* Chris and Chrissy Rouse
* Kirsty MacColl
* Agnes Milowka
* François de Roubaix
* Dave Shaw
* Wesley C. Skiles
* Dewey Smith
* Rob Stewart
* Esbjörn Svensson
* Josef Velek

Publications

| Manuals|

* NOAA Diving Manual
* U.S. Navy Diving Manual
* Basic Cave Diving: A Blueprint for Survival
* Underwater Handbook
* Bennett and Elliott's physiology and medicine of diving
* Encyclopedia of Recreational Diving
* The new science of skin and scuba diving
* Professional Diver's Handbook
* Basic Scuba

|

Standards and
Codes of Practice|

* Code of Practice for Scientific Diving (UNESCO)
* DIN 7876
* IMCA Code of Practice for Offshore Diving
* ISO 24801 Recreational diving services — Requirements for the training of recreational scuba divers

General non-fiction|

* The Darkness Beckons
* Goldfinder
* The Last Dive
* Shadow Divers
* The Silent World: A Story of Undersea Discovery and Adventure

Research|

* List of Divers Alert Network publications

Dive guides|

Training and registration

| Diver
training|

* Competence and assessment
* Competency-based learning
* Refresher training
* Skill assessment
* Diver training standard
* Diving instructor
* Diving school
* Occupational diver training
* Commercial diver training
* Military diver training
* Public safety diver training
* Scientific diver training
* Recreational diver training
* Introductory diving
* Teaching method
* Muscle memory
* Overlearning
* Stress exposure training

| Skills|

* Combat sidestroke
* Diver navigation
* Diver trim
* Ear clearing
* Frenzel maneuver
* Valsalva maneuver
* Finning techniques
* Scuba skills
* Buddy breathing
* Low impact diving
* Diamond Reef System
* Surface-supplied diving skills
* Underwater searches

|

Recreational
scuba
certification
levels|

| Core diving skills|

* Advanced Open Water Diver
* Autonomous diver
* CMAS* scuba diver
* CMAS** scuba diver
* Introductory diving
* Low Impact Diver
* Master Scuba Diver
* Open Water Diver
* Supervised diver

|

Leadership skills|

* Dive leader
* Divemaster
* Diving instructor
* Master Instructor

Specialist skills|

* Rescue Diver
* Solo diver

Diver training
certification
and registration
organisations|

* European Underwater Federation (EUF)
* International Diving Regulators and Certifiers Forum (IDRCF)
* International Diving Schools Association (IDSA)
* International Marine Contractors Association (IMCA)
* List of diver certification organizations
* National Oceanic and Atmospheric Administration (NOAA)
* Nautical Archaeology Society
* Universal Referral Program
* World Recreational Scuba Training Council (WRSTC)

| Commercial diver
certification
authorities|

* Australian Diver Accreditation Scheme (ADAS)
* Commercial diver registration in South Africa
* Divers Institute of Technology
* Health and Safety Executive (HSE)
* Department of Employment and Labour

|

Commercial diving
schools|

* Divers Academy International
* Norwegian diver school

Free-diving
certification
agencies|

* AIDA International (AIDA)
* Confédération Mondiale des Activités Subaquatiques (CMAS)
* Performance Freediving International (PI)
* Scuba Schools International (SSI)

Recreational scuba
certification
agencies|

* American Canadian Underwater Certifications (ACUC)
* American Nitrox Divers International (ANDI)
* Association nationale des moniteurs de plongée (ANMP)
* British Sub-Aqua Club (BSAC)
* Comhairle Fo-Thuinn (CFT)
* Confédération Mondiale des Activités Subaquatiques (CMAS)
* Federación Española de Actividades Subacuáticas (FEDAS)
* Fédération Française d'Études et de Sports Sous-Marins (FFESSM)
* Federazione Italiana Attività Subacquee (FIAS)
* Global Underwater Explorers (GUE)
* International Association for Handicapped Divers (IAHD)
* International Association of Nitrox and Technical Divers (IANTD)
* International Diving Educators Association (IDEA)
* Israeli Diving Federation (TIDF)
* National Academy of Scuba Educators (NASE)
* National Association of Underwater Instructors (NAUI)
* Nederlandse Onderwatersport Bond (NOB)
* Professional Association of Diving Instructors (PADI)
* Professional Diving Instructors Corporation (PDIC)
* Sub-Aqua Association (SAA)
* Scuba Diving International (SDI)
* Scuba Educators International (SEI)
* Scottish Sub Aqua Club (ScotSAC)
* Scuba Schools International (SSI)
* Türkiye Sualtı Sporları Federasyonu (TSSF)
* United Diving Instructors (UDI)
* YMCA SCUBA Program

Scientific diver
certification
authorities|

* American Academy of Underwater Sciences (AAUS)
* CMAS Scientific Committee

Technical
certification
agencies|

* American Nitrox Divers International (ANDI)
* British Sub-Aqua Club (BSAC)
* Confédération Mondiale des Activités Subaquatiques (CMAS)
* Diving Science and Technology (DSAT)
* Federazione Italiana Attività Subacquee (FIAS)
* International Association of Nitrox and Technical Divers (IANTD)
* Professional Association of Diving Instructors (PADI)
* Professional Diving Instructors Corporation (PDIC)
* Trimix Scuba Association (TSA)
* Technical Extended Range (TXR)

| Cave
diving|

* Cave Divers Association of Australia (CDAA)
* Cave Diving Group (CDG)
* Global Underwater Explorers (GUE)
* National Association for Cave Diving (NACD)
* National Speleological Society#Cave Diving Group (CDG)
* National Association of Underwater Instructors (NAUI)
* Technical Diving International (TDI)

|

Underwater sports

| Surface snorkeling|

* Finswimming

|

Snorkeling/breath-hold|

* Spearfishing
* Underwater football
* Underwater hockey
* Australia
* Turkey
* Underwater rugby
* Colombia
* United States
* Underwater target shooting

Breath-hold|

* Aquathlon
* Apnoea finswimming
* Freediving
* Underwater ice hockey

Open Circuit Scuba|

* Immersion finswimming
* Sport diving
* Underwater cycling
* Underwater orienteering
* Underwater photography

Rebreather|

* Underwater photography

Sports governing
organisations
and federations|

* International
* AIDA International
* Confédération Mondiale des Activités Subaquatiques)
* National
* AIDA Hellas
* Australian Underwater Federation
* British Freediving Association
* British Octopush Association
* British Underwater Sports Association
* Comhairle Fo-Thuinn
* Federación Española de Actividades Subacuáticas
* Fédération Française d'Études et de Sports Sous-Marins
* South African Underwater Sports Federation
* Türkiye Sualtı Sporları Federasyonu
* Underwater Society of America)

Competitions|

* 14th CMAS Underwater Photography World Championship

Underwater divers

| Pioneers
of diving|

* Eduard Admetlla i Lázaro
* Aquanaut
* James F. Cahill
* Jacques Cousteau
* Billy Deans
* Dottie Frazier
* Hans Hass
* Dick Rutkowski
* Teseo Tesei
* Arne Zetterström

|

Underwater
scientists
archaeologists and
environmentalists|

* Michael Arbuthnot
* Robert Ballard
* George Bass
* Mensun Bound
* Louis Boutan
* Hugh Bradner
* Cathy Church
* Eugenie Clark
* James P. Delgado
* Sylvia Earle
* John Christopher Fine
* George R. Fischer
* Anders Franzén
* Honor Frost
* Fernando Garfella Palmer
* David Gibbins
* Graham Jessop
* Swietenia Puspa Lestari
* Pilar Luna
* Robert F. Marx
* Anna Marguerite McCann
* Innes McCartney
* Charles T. Meide
* David Moore
* Mark M. Newell
* Lyuba Ognenova-Marinova
* John Peter Oleson
* Mendel L. Peterson
* Richard Pyle
* William R. Royal
* Margaret Rule
* Gunter Schöbel
* Stephanie Schwabe
* Myriam Seco
* E. Lee Spence
* Robert Sténuit
* Peter Throckmorton

Scuba record
holders|

* Pascal Bernabé
* Jim Bowden
* Mark Ellyatt
* Sheck Exley
* Nuno Gomes
* Claudia Serpieri
* Krzysztof Starnawski

Underwater
filmmakers
and presenters|

* Samir Alhafith
* David Attenborough
* Ramón Bravo
* Jean-Michel Cousteau
* Richie Kohler
* Ivan Tors
* Andrew Wight

Underwater
photographers|

* Tamara Benitez
* Georges Beuchat
* Adrian Biddle
* Jonathan Bird
* Eric Cheng
* Neville Coleman
* Jacques Cousteau
* John D. Craig
* Ben Cropp
* Bernard Delemotte
* David Doubilet
* John Christopher Fine
* Dermot FitzGerald
* Rodney Fox
* Ric Frazier
* Stephen Frink
* Peter Gimbel
* Monty Halls
* Hans Hass
* Henry Way Kendall
* Rudie Kuiter
* Joseph B. MacInnis
* Luis Marden
* Agnes Milowka
* Noel Monkman
* Steve Parish
* Zale Parry
* Pierre Petit
* Leni Riefenstahl
* Peter Scoones
* Brian Skerry
* Wesley C. Skiles
* E. Lee Spence
* Philippe Tailliez
* Ron Taylor
* Valerie Taylor
* Albert Tillman
* John Veltri
* Stan Waterman
* Michele Westmorland
* John Ernest Williamson
* J. Lamar Worzel

Underwater
explorers|

* Caves
* Graham Balcombe
* Sheck Exley
* Martyn Farr
* Jochen Hasenmayer
* Jill Heinerth
* Jarrod Jablonski
* William Hogarth Main
* Tom Mount
* Jack Sheppard
* Bill Stone
* Reefs
*   * Wrecks
* Leigh Bishop
* John Chatterton
* Clive Cussler
* Bill Nagle
* Aristotelis Zervoudis

Aquanauts|

* Andrew Abercromby
* Joseph M. Acaba
* Clayton Anderson
* Richard R. Arnold
* Serena Auñón-Chancellor
* Michael Barratt (astronaut)
* Robert L. Behnken
* Randolph Bresnik
* Timothy J. Broderick
* Justin Brown
* Berry L. Cannon
* Scott Carpenter
* Gregory Chamitoff
* Steve Chappell
* Catherine Coleman
* Robin Cook
* Craig B. Cooper
* Fabien Cousteau
* Philippe Cousteau
* Timothy Creamer
* Jonathan Dory
* Pedro Duque
* Sylvia Earle
* Jeanette Epps
* Sheck Exley
* Albert Falco
* Andrew J. Feustel
* Michael Fincke
* Satoshi Furukawa
* Ronald J. Garan Jr.
* Michael L. Gernhardt
* Christopher E. Gerty
* David Gruber
* Chris Hadfield
* Jeremy Hansen
* José M. Hernández
* John Herrington
* Paul Hill
* Akihiko Hoshide
* Mark Hulsbeck
* Emma Hwang
* Norishige Kanai
* Les Kaufman
* Scott Kelly
* Karen Kohanowich
* Timothy Kopra
* Dominic Landucci
* Jon Lindbergh
* Kjell N. Lindgren
* Michael López-Alegría
* Joseph B. MacInnis
* Sandra Magnus
* Thomas Marshburn
* Matthias Maurer
* K. Megan McArthur
* Craig McKinley
* Jessica Meir
* Simone Melchior
* Dorothy Metcalf-Lindenburger
* Andreas Mogensen
* Karen Nyberg
* John D. Olivas
* Takuya Onishi
* Luca Parmitano
* Nicholas Patrick
* Tim Peake
* Thomas Pesquet
* Marc Reagan
* Garrett Reisman
* Kathleen Rubins
* Dick Rutkowski
* Tara Ruttley
* David Saint-Jacques
* Josef Schmid
* Robert Sheats
* Dewey Smith
* Steve Squyres
* Heidemarie Stefanyshyn-Piper
* Robert Sténuit
* Hervé Stevenin
* Nicole Stott
* James Talacek
* Daniel M. Tani
* Robert Thirsk
* Bill Todd
* Mark T. Vande Hei
* Koichi Wakata
* Rex J. Walheim
* Shannon Walker
* John Morgan Wells
* Joachim Wendler
* Douglas H. Wheelock
* Peggy Whitson
* Dafydd Williams
* Jeffrey Williams
* Sunita Williams
* Gregory R. Wiseman
* Kimiya Yui

Writers and journalists|

* Michael C. Barnette
* Victor Berge
* Philippe Diolé
* Gary Gentile
* Bret Gilliam
* Bob Halstead
* Trevor Jackson
* Steve Lewis
* John Mattera

Rescuers|

* Craig Challen
* Richard Harris
* Rick Stanton
* John Volanthen

Frogmen|

* Lionel Crabb

Commercial salvors|

* Keith Jessop

Science of underwater diving

| Diving
physics|

* Breathing performance of regulators
* Buoyancy
* Archimedes' principle
* Neutral buoyancy
* Concentration
* Diffusion
* Molecular diffusion
* Force
* Oxygen fraction
* Permeation
* Psychrometric constant
* Solubility
* Henry's law
* Saturation
* Solution
* Supersaturation
* Surface tension
* Hydrophobe
* Surfactant
* Temperature
* Torricellian chamber
* Underwater acoustics
* Modulated ultrasound
* Underwater vision
* Snell's law
* Underwater computer vision
* Weight
* Apparent weight

| Gas laws|

* Amontons's law
* Boyle's law
* Charles's law
* Combined gas law
* Dalton's law
* Gay-Lussac's law
* Ideal gas law

|

Pressure|

* Absolute pressure
* Ambient pressure
* Atmospheric pressure
* Gauge pressure
* Hydrostatic pressure
* Metre sea water
* Partial pressure

Diving
physiology|

* Artificial gills
* Cold shock response
* Diving reflex
* Equivalent narcotic depth
* Lipid
* Maximum operating depth
* Metabolism
* Physiological response to water immersion
* Tissue
* Underwater vision

| Circulatory
system|

* Blood shift
* Patent foramen ovale
* Perfusion
* Pulmonary circulation
* Systemic circulation

|

Decompression
theory|

* Decompression models:
* Bühlmann decompression algorithm
* Haldane's decompression model
* Reduced gradient bubble model
* Thalmann algorithm
* Thermodynamic model of decompression
* Varying Permeability Model
* Equivalent air depth
* Equivalent narcotic depth
* Oxygen window in diving decompression
* Physiology of decompression

Respiration|

* Blood–air barrier
* Breathing
* CO₂ retention
* Dead space
* Gas exchange
* Hypocapnia
* Respiratory exchange ratio
* Respiratory quotient
* Respiratory system
* Work of breathing

Diving
environment|

| Classification|

* List of diving environments by type
* Altitude diving
* Benign water diving
* Confined water diving
* Deep diving
* Inland diving
* Inshore diving
* Muck diving
* Night diving
* Open-water diving
* Black-water diving
* Blue-water diving
* Penetration diving
* Cave diving
* Ice diving
* Wreck diving
* Recreational dive sites
* Underwater environment

|

Impact|

* Environmental impact of recreational diving
* Low impact diving

Environmental
factors|

* Algal bloom
* Currents:
* Current
* Longshore drift
* Ocean current
* Rip current
* Tidal race
* Undertow
* Upwelling
* Ekman transport
* Halocline
* Reef
* Coral reef
* Stratification
* Thermocline
* Tides
* Turbidity
* Wind wave
* Breaking wave
* Surf
* Surge
* Wave shoaling

Other

* Bathysphere
* Defense against swimmer incursions
* Diver detection sonar
* Offshore survey
* Underwater domain awareness

| Awards and events|

* Hans Hass Award
* International Scuba Diving Hall of Fame
* London Diving Chamber Dive Lectures
* NOGI Awards

|

Deep-submergence
vehicle|

* Aluminaut
* DSV Alvin
* American submarine NR-1
* Bathyscaphe
* Archimède
* FNRS-2
* FNRS-3
* FNRS-4
* Harmony class bathyscaphe
* Sea Pole-class bathyscaphe
* Trieste II
* Deepsea Challenger
* Ictineu 3
* JAGO
* Jiaolong
* Konsul-class submersible
* DSV Limiting Factor
* Russian submarine Losharik
* Mir
* Nautile
* Pisces-class deep submergence vehicle
* DSV Sea Cliff
* DSV Shinkai
* DSV Shinkai 2000
* DSV Shinkai 6500
* DSV Turtle
* DSV-5 Nemo

| Deep-submergence
rescue vehicle|

* LR5
* LR7
* MSM-1
* Mystic-class deep-submergence rescue vehicle
* DSRV-1 Mystic
* DSRV-2 Avalon
* NATO Submarine Rescue System
* Priz-class deep-submergence rescue vehicle
* Russian deep submergence rescue vehicle AS-28
* Russian submarine AS-34
* ASRV Remora
* SRV-300
* Submarine Rescue Diving Recompression System
* Type 7103 DSRV
* URF (Swedish Navy)

|

Special
interest
groups|

* Artificial Reef Society of British Columbia
* CMAS Europe
* Coral Reef Alliance
* Diving Equipment and Marketing Association
* Divers Alert Network
* Green Fins
* Historical Diving Society
* Karst Underwater Research
* Nautical Archaeology Program
* Nautical Archaeology Society
* Naval Air Command Sub Aqua Club
* Project AWARE
* Reef Check
* Reef Life Survey
* Rubicon Foundation
* Save Ontario Shipwrecks
* SeaKeys
* Sea Research Society
* Society for Underwater Historical Research
* Society for Underwater Technology
* Underwater Archaeology Branch, Naval History & Heritage Command

Submarine escape
and rescue|

* Escape trunk
* International Submarine Escape and Rescue Liaison Office
* McCann Rescue Chamber
* Submarine Escape and Rescue system (Royal Swedish Navy)
* Submarine escape training facility
* Submarine Escape Training Facility (Australia)
* Submarine rescue ship

Neutral buoyancy
facilities for
Astronaut training|

* Neutral Buoyancy Laboratory
* Neutral buoyancy pool
* Neutral buoyancy simulation as a training aid
* Neutral Buoyancy Simulator
* Space Systems Laboratory
* Yuri Gagarin Cosmonaut Training Center

Other|

* Nautilus Productions

* Category
* Commons
*   * Glossary
* Indexes: dive sites
* divers
* diving
*   * Outline
* Portal

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