Underwater acoustic positioning system

Short description: System for tracking and navigation of underwater vehicles or divers using acoustic signals

An underwater acoustic positioning system[1][2] is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation. Underwater acoustic positioning systems are commonly used in a wide variety of underwater work, including oil and gas exploration, ocean sciences, salvage operations, marine archaeology, law enforcement and military activities.

## Contents

* 1 Method of operation
* 1.1 Baseline station deployment and survey
* 1.2 Tracking or navigation operations
* 2 Classes
* 3 History and examples of use
* 4 References
* 5 External links

## Method of operation

The general method of operation of an acoustic positioning system is described for an example of a long baseline (LBL) positioning system for a ROV[3]

### Baseline station deployment and survey

Method of operation of a Long Baseline (LBL) acoustic positioning system for ROV
A: interrogator, B, C, D, E: baseline transponders, F: ROV umbilical

Acoustic positioning systems measure positions relative to a framework of baseline stations, which must be deployed prior to operations. In the case of a long-baseline (LBL) system, a set of three or more baseline transponders are deployed on the sea floor. The location of the baseline transponders either relative to each other or in global coordinates must then be measured precisely. Some systems assist this task with an automated acoustic self-survey, and in other cases GPS is used to establish the position of each baseline transponder as it is deployed or after deployment.[3]

### Tracking or navigation operations

Following the baseline deployment and survey, the acoustic positioning system is ready for operations. In the long baseline example an interrogator is mounted on the ROV that is to be tracked. The interrogator transmits an acoustic signal that is received by the baseline transponders. The reply of the baseline transponders is received again at the ROV. The signal time-of-flight or the corresponding distances between interrogator and baseline transponders are transmitted via the ROV umbilical to the surface, where the ROV position is computed and displayed on a tracking screen. The acoustic distance measurements may be augmented by depth sensor data to obtain better positioning accuracy in the three-dimensional underwater space.[3]

Acoustic positioning systems can yield an accuracy of a few centimeters to tens of meters and can be used over operating distance from tens of meters to tens of kilometers. Performance depends strongly on the type and model of the positioning system, its configuration for a particular job, and the characteristics of the underwater acoustic environment at the work site.[3]

## Classes

Underwater acoustic positioning systems are generally categorized into three broad types or classes[4][5][6]

Long-baseline (LBL) systems, use a sea-floor baseline transponder network. The transponders are typically mounted in the corners of the operations site. LBL systems yield very high accuracy of generally better than 1 m and sometimes as good as 0.01m along with very robust positions[7][8] This is due to the fact that the transponders are installed in the reference frame of the work site itself (i.e. on the sea floor), the wide transponder spacing results in an ideal geometry for position computations, and the LBL system operates without an acoustic path to the (potentially distant) sea surface.

Ultra-short-baseline (USBL) systems and the related super-short-baseline (SSBL) systems rely on a small (ex. 230 mm across), tightly integrated transducer array that is typically mounted on the bottom end of a strong, rigid transducer pole which is installed either on the side or in some cases on the bottom of a surface vessel.[9][10] Unlike LBL and SBL systems, which determine position by measuring multiple distances, the USBL transducer array is used to measure the target distance from the transducer pole by using signal run time, and the target direction by measuring the phase shift of the reply signal as seen by the individual elements of the transducer array. The combination of distance and direction fixes the position of the tracked target relative to the surface vessel. Additional sensors including GPS, a gyro or electronic compass and a vertical reference unit are then used to compensate for the changing position and orientation (pitch, roll, bearing) of the surface vessel and its transducer pole. USBL systems offer the advantage of not requiring a sea floor transponder array. The disadvantage is that positioning accuracy and robustness is not as good as for LBL systems. The reason is that the fixed angle resolved by a USBL system translates to a larger position error at greater distance. Also, the multiple sensors needed for the USBL transducer pole position and orientation compensation each introduce additional errors. Finally, the non-uniformity of the underwater acoustic environment cause signal refractions and reflections that have a greater impact on USBL positioning than is the case for the LBL geometry.

Short-baseline (SBL) systems use a baseline consisting of three or more individual sonar transducers that are connected by wire to a central control box. Accuracy depends on transducer spacing and mounting method. When a wider spacing is employed as when working from a large working barge or when operating from a dock or other fixed platform, the performance can be similar to LBL systems. When operating from a small boat where transducer spacing is tight, accuracy is reduced. Like USBL systems, SBL systems are frequently mounted on boats and ships, but specialized modes of deployment are common too. For example, the Woods Hole Oceanographic Institution uses a SBL system to position the Jason deep-ocean ROV relative to its associated MEDEA depressor weight with a reported accuracy of 9 cm[11]

GPS intelligent buoys (GIB) systems are inverted LBL devices where the transducers are replaced by floating buoys, self-positioned by GPS. The tracked position is calculated in realtime at the surface from the Time-Of-Arrival (TOAs) of the acoustic signals sent by the underwater device, and acquired by the buoys. Such configuration allow fast, calibration-free deployment with an accuracy similar to LBL systems. At the opposite of LBL, SBL or USBL systems, GIB systems use one-way acoustic signals from the emitter to the buoys, making it less sensitive to surface or wall reflections. GIB systems are used to track AUVs, torpedoes, or divers, may be used to localize airplanes black-boxes, and may be used to determine the impact coordinates of inert or live weapons for weapon testing and training purposes[12][13][14]

## History and examples of use

An acoustic short baseline (SBL) positioning system was installed on the USNS Mizar during the search dives to the wreckage of the submarine USS Thresher The bathyscaphe Trieste was guided by its acoustic positioning system to the Thresher

An early use of underwater acoustic positioning systems, credited with initiating the modern day development of these systems,[15] involved the loss of the American nuclear submarine USS Thresher on 10 April 1963 in a water depth of 2560m.[16] An acoustic short baseline (SBL) positioning system was installed on the oceanographic vessel USNS Mizar. This system was used to guide the bathyscaphe Trieste 1 to the wreck site. Yet, the state of the technology was still so poor that out of ten search dives by Trieste 1, visual contact was only made once with the wreckage.[17] Acoustic positioning was again used in 1966, to aid in the search and subsequent recovery of a nuclear bomb lost during the crash of a B-52 bomber at sea off the coast of Spain.

In the 1970s, oil and gas exploration in deeper waters required improved underwater positioning accuracy to place drill strings into the exact position referenced earlier thorough seismic instrumentation[18] and to perform other underwater construction tasks.

The Russian deep sea submersibles MIR-1 and MIR-2 searched the wreck site of the Japanese submarine I-52 in 1998. A LBL positioning system was used to guide and document the progressing search over multiple dives

The technology was also used in other applications. In 1998, salvager Paul Tidwell's company Cape Verde Explorations led an expedition to the wreck site of the World War 2 Japanese cargo submarine I-52 in the mid-Atlantic.[19] Resting at a depth of 5240 meters, it had been located and then identified using side scan sonar and an underwater tow sled in 1995. War-time records indicated the I-52 was bound for Germany, with a cargo including 146 gold bars in 49 metal boxes. Tidwell's company had hired the Russian oceanographic vessel, the Akademik Mstislav Keldysh with its two crewed deep-ocean submersibles MIR-1 and MIR-2. In order to facilitate precise navigation across the debris field and assure a thorough search, MIR-1 deployed a long baseline transponder network on the first dive. Over a series of seven dives by each submersible, the debris field was progressively searched. The LBL positioning record indicated the broadening search coverage after each dive, allowing the team to concentrate on yet unsearched areas during the following dive. No gold was found, but the positioning system had documented the extent of the search.

In recent years, several trends in underwater acoustic positioning have emerged. One is the introduction of compound systems such the combination of LBL and USBL in a so-called LUSBL[20] configuration to enhance performance. These systems are generally used in the offshore oil & gas sector and other high-end applications. Another trend is the introduction of compact, task optimized systems for a variety of specialized purposes. For example, the California Department of Fish and Game commissioned a system, which continually measures the opening area and geometry of a fish sampling net during a trawl. That information helps the department improve the accuracy of their fish stock assessments in the Sacramento River Delta.

NetTrack is an example of a special-purpose underwater acoustic positioning system of the SBL type, designed to measure the opening geometry and area of a trawl net for accurate fish stock assessment purposes. Left: Four small responders (A, B, C, D) are mounted in the corners of the trawl net opening and wired via junction bottle (E) and umbilical (F) to a surface station computer. Center: The net is deployed. Right: The surface station computer sends instructions to one responder (ex. A) to transmit, while instructing the other responders (ex. B, C, D) to receive. By this method all six distances (A–B, A–C, A–D, B–C, B–D, C–D) are measured. The four sides of the opening and one diagonal are used to triangulate the trawl net opening geometry and area. The second diagonal is available to compute a measurement error metric for data quality verification.

Water-proof smart devices like Apple Watch Ultra and Garmin Descent have been introduced to function as dive computers. These devices have a depth gauge sensor, provide a dive profile, and safety alerts for fast ascents and decompression stops using the depth data. In 2023, University of Washington researchers demonstrated a fourth class of 3D underwater positioning for these smart devices that does not require infrastructure support like buoys.[21] Instead they use distributed localization techniques[22] by computing the pairwise distances between a network of diver devices to determine the shape of the resulting network topology. Combining this with depth sensor data from these devices, the lead diver can then compute the relative 3D positions of all the other diver devices.

## References

1. ↑ "Discovery of Sound in the Sea". University of Rhode Island. http://www.dosits.org/gallery/tech/n/at1.htm.
2. ↑ Milne, P.H. (1983). Underwater Acoustic Positioning Systems. Gulf Publishing Company, Book Division. ISBN 0-87201-012-0.
3. ↑ 3.0 3.1 3.2 3.3 Christ, Robert D.; Wernli, Robert L. (2007). The ROV Manual. pp. 96–103. ISBN 978-0-7506-8148-3.
4. ↑ "A Smooth Operator's Guide to Underwater Sonars and Acoustic Devices" (in en-US). https://bluerobotics.com/learn/a-smooth-operators-guide-to-underwater-sonars-and-acoustic-devices/.
5. ↑ Milne 1983, chapters 3-5
6. ↑ Christ & Wernli 2007, sections 4.2.6-4.2.7
7. ↑ "MIT Deepwater Archaeology Research Group". http://web.mit.edu/deeparch/www/research/precisionnav.html.
8. ↑ Foley, B.P.; Mindell, D.A. (2002). "Precision Survey and Archaeological Methodology in Deep Water". ENALIA the Journal of the Hellenic Institute of Marine Archaeology VI: 9–56. http://web.mit.edu/deeparch/www/publications/papers/FoleyMindell2002.pdf.
9. ↑ Milne 1983, chapter 4
10. ↑ Christ & Wernli 2007, section 4.2.6.3
11. ↑ Bingham, Brian; Mindell, David; Wilcox, Thomas; Bowen, Andy (Spring 2006). "Integrating Precision Relative Positioning Into JASON/MEDEA ROV Operations". Marine Technology Society Journal 40 (1): 87. doi:10.4031/002533206787353664. Bibcode: 2006MTSJ...40a..87B. http://web.mit.edu/mindell/www/Publications/MTSsharpspaper.pdf.
12. ↑ Kayser, Jack R.; Cardoza, Miguel A.; Wade, William F.; Merts, John H.; Casey, David R. (24–26 January 2005). "﻿Weapon Scoring Results from a GPS Acoustic Weapons Test and Training System﻿". Institute of Navigation National Technical Meeting (San Diego, CA). http://www.tridentresearch.com/pubs/Weapon_Scoring_Results_from_GPS_Acoustic_System.pdf.
13. ↑ Cardoza, M.A.; Kayser, J.R.; Wade, B. (April 2006). "Offshore Scoring of Precision Guided Munitions". pp. 32–39. http://www.tridentresearch.com/pubs/InsideGNSS_8x11.pdf.
14. ↑ Cardoza, Miguel A.; Kayser, Jack R.; Wade, William F.; Bennett, Richard L.; Merts, John H.; Casey, David R. (10 March 2005). "Offshore Weapon Scoring Using Rapidly Deployed Realtime Acoustic Sensors". 21st Annual National Test & Evaluation Conference. Charlotte, North Carolina. https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/test/tk9.pdf.
15. ↑ Milne 1983, Chapter 2
16. ↑ Christ & Wernli 2007, p. 96
17. ↑ Milne 1983, Chapter 3
18. ↑ Christ & Wernli 2007, section 4.2.1
19. ↑ The Last Dive, National Geographic Magazine October 1999
20. ↑ Davis (2002). "Flexible Acoustic Positioning System Architecture". MTS Dynamic Positioning Conference 2002. http://www.dynamic-positioning.com/dp2002/acoustics_flexible_davis.pdf. Retrieved 2009-03-10.
21. ↑ Chen, Tuochao; Chan, Justin; Gollakota, Shyamnath (2023-09-10). "Underwater 3D positioning on smart devices" (in en). Proceedings of the ACM SIGCOMM 2023 Conference. ACM. pp. 33–48. doi:10.1145/3603269.3604851. ISBN 979-8-4007-0236-5. https://dl.acm.org/doi/10.1145/3603269.3604851.
22. ↑ Alrajeh, Nabil Ali; Bashir, Maryam; Shams, Bilal (2013-06-01). "Localization Techniques in Wireless Sensor Networks" (in en). International Journal of Distributed Sensor Networks 9 (6). doi:10.1155/2013/304628. ISSN 1550-1477.

## External links

* Safran Electronics & Defense Naval solutions
* IXBLUE Subsea navigation and positioning
* Underwater GPS at ACSA Underwater GPS

* v
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* e

Hydroacoustics

Sonar|

* Active acoustics
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Ocean acoustics|

* Acoustic network
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* Underwater acoustics
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* Underwater acoustic positioning system

Acoustic ecology|

* Acoustic survey in fishing
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* Hearing range of marine mammals
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Related topics|

* Acoustic signature
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Template:Positioning systems

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Underwater diving

* Diving modes
* Atmospheric pressure diving
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Diving equipment

| Basic equipment|

* Diving mask
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|

Breathing gas|

* Bailout gas
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Buoyancy and
trim equipment|

* Buoyancy control device
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Decompression
equipment|

* Decompression buoy
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Environmental
protection|

* Atmospheric diving suit
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Helmets
and masks|

* Anti-fog
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Instrumentation|

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Mobility
equipment|

* Diving bell
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Safety
equipment|

* Alternative air source
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* Dive light
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* Diver's cutting tool
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* Diving bell
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* Emergency gas supply
* Lifeline
* Screw gate carabiner
* Line marker
* Octopus regulator
* Pony bottle
* Rescue tether
* Safety helmet
* Shark-proof cage
* Surface marker buoy
* Personal locator beacon

Underwater
breathing
apparatus|

* Atmospheric diving suit
* Diving cylinder
* Burst disc
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* Single-hose regulator
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* Viper
* Surface-supplied diving equipment
* Air line
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* Hookah
* Sea Trek
* Snuba
* Standard diving dress

Diving
equipment
manufacturers|

* AP Diving
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* Oceanic Worldwide
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* Shearwater Research
* Siebe Gorman
* Submarine Products
* Suunto

Diving support equipment

| Breathing gas|

* Air filtration
* Booster pump
* Carbon dioxide scrubber
* Cascade filling system
* Diver's pump
* Diving air compressor
* Diving air filter
* 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 method of gas concentration
* Pressure swing adsorption
* Oxygen analyser
* Oxygen compatibility

|

Decompression
equipment|

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

Platforms|

* Dive boat
* Boarding stirrup
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* Tektite habitat

Remotely operated
underwater vehicles|

* 8A4-class ROUV
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* Seabed tractor
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* 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 ladder
* Hot water system
* Downline

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
* Fins
* Hawaiian sling
* Monofin
* Polespear
* Snorkel (swimming)
* Speargun
* 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 diving
* Commercial offshore diving
* Hazmat diving
* Divemaster
* Diving instructor
* Diving safety officer
* Diving supervisor
* Haenyeo
* Media diving
* Underwater photography
* Underwater videography
* Military diving
* Army engineer diver
* Clearance diver
* Frogman
* Police diving
* Public safety diving
* Scientific diving
* Underwater archaeology

|

Underwater work|

* Commercial offshore diving
* Dive guide
* Diver training
* Recreational diver training
* Hyperbaric welding
* Nondestructive testing
* Pearl hunting
* Police diving
* Public safety diving
* Salvage diving
* Scientific diving
* Sponge diving
* Submarine pipeline
* Underwater archaeology
* Underwater demolition
* Underwater photography
* Underwater search and recovery
* Underwater videography

Tools & equipment|

* Abrasive waterjet
* Airlift
* In-water surface cleaning
* Brush cart
* Cavitation cleaning
* Pressure washing
* Lifting bag
* Remotely operated underwater vehicle
* Silt screw
* Snoopy loop
* 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
* 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|

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

Recreational
dive sites|

| Reef diving
regions|

* Arrecifes de Cozumel National 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
* Palancar Reef
* Underwater artworks
* Cancún Underwater Museum
* Christ of the Abyss
* The Diver
* Molinere Underwater Sculpture Park

Wreck diving
regions|

* Chuuk Lagoon
* Maritime Heritage Trail – Battle of Saipan
* Whitefish Point Underwater Preserve
* Wreck Alley, San Diego

Wreck dive
sites|

* HMS A1
* HMS A3
* Engineering:USS Aaron Ward
* Abessinia
* Aeolian Sky
* Albert C. Field
* Andrea Doria
* Antilla
* Antilles
* Aquila
* Engineering:USS Arkansas
* HMS Boadicea
* Bianca C.
* Booya
* HMSAS Bloemfontein
* Breda
* HMAS Brisbane
* 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
* Engineering: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
* Engineering:USS Oriskany
* Oslofjord
* P29
* P31
* Pedernales
* Persier
* HMAS Perth
* SAS Pietermaritzburg
* Piłsudski
* Pool Fisher
* HMS Port Napier
* Preußen
* President Coolidge
* PS Queen Victoria
* Radaas
* Error: {{Ship}} missing prefix (help)
* RMS Rhone
* Rondo
* Rosehill
* Error: {{Ship}} missing prefix (help)
* Royal Charter
* Rozi
* HMS Safari
* Salem Express
* Engineering:USS Saratoga
* Engineering:USS Scuffle
* HMS Scylla
* HMS Sidon
* Engineering:USS Spiegel Grove
* Stanegarth
* Stanwood
* Stella
* HMAS Swan
* Engineering:USS Tarpon
* Thesis
* Thistlegorm
* Toa Maru
* Torrey Canyon
* SAS Transvaal
* Tulagi
* Tulamben
* U-40
* U-352
* U-1195
* Um El Faroud
* Varvassi
* Walter L M Russ
* Washingtonian (1913)
* HMNZS Wellington
* Engineering:USS Yancey
* Yongala
* Zenobia
* Zealandia
* Zingara

Cave diving
sites|

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

Freshwater
dives|

* Ewens Ponds
* Little Blue Lake

Training sites|

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

Open ocean
diving|

* Blue-water diving
* Black-water diving

Diving safety

* Ergonomics of diving equipment
* Human factors in diving safety
* Life support system
* Safety-critical system

| Diving hazards|

* Trait anxiety
* Cold shock response
* Decompression
* List of diving hazards and precautions
* Nitrogen narcosis
* Overconfidence effect
* Oxygen toxicity
* Panic
* Penetration diving
* Seasickness
* Silt out
* Single point of failure
* Task loading
* Uncontrolled decompression

|

Consequences|

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

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's attendant
* Diving supervisor
* Diving systems technician
* Life support technician
* Stand-by diver
* Equipment safety
* Breathing gas quality
* Testing and inspection of diving cylinders
* Hydrostatic test
* Sustained load cracking
* Diving regulators
* 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
* Health and safety representative
* Operations manual
* Safety meeting
* Standard operating procedure

Diving
procedures|

* Ascending and descending
* Emergency ascent
* Boat diving
* Canoe and kayak diving
* Buddy diving
* 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

Incidents|

| Diver rescues|

* Tham Luang cave rescue

|

Early diving|

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

Freediving|

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

Professional
diving|

* Johnson Sea Link accident
* Offshore diving incidents
* Byford Dolphin diving bell accident
* Drill Master diving accident
* Star Canopus diving accident
* Venture One diving accident
* Waage Drill II diving accident
* Wildrake diving accident
* Professional diver fatalities
* Roger Baldwin
* John Bennett
* Victor F. Guiel Jr.
* Craig M. Hoffman
* Peter Henry Michael Holmes
* Edwin Clayton Link
* Gerard Anthony Prangley
* Pier Skipness
* Robert John Smyth
* Albert D. Stover
* Richard A. Walker
* Lothar Michael Ward
* Joachim Wendler
* Death of 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
* 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

Diving medicine

| Diving
disorders|

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

| Pressure
related|

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

| 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
* 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
* 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
* Duty of care
* List of legislation regulating underwater diving
* Investigation of diving accidents

History of underwater diving

* Aqua-Lung
* History of decompression research and development
* History of scuba diving
* List of researchers in underwater diving
* Porpoise regulator
* Standard diving dress
* Timeline of diving technology
* Underwater diving in popular culture
* Vintage scuba

Publications

| Manuals|

* NOAA Diving Manual
* U.S. Navy Diving Manual
* Basic Cave Diving: A Blueprint for Survival

|

Standards and
Codes of Practice|

* DIN 7876

General non-fiction|

* The Darkness Beckons
* Goldfinder
* The Last Dive
* Shadow Divers

Training and registration

| Diver
training|

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

|

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

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 Association for Cave Diving (NACD)
* 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

Recreational scuba
certification
levels|

* Advanced Open Water Diver
* Autonomous diver
* CMAS* scuba diver
* CMAS** scuba diver
* Dive leader
* Divemaster
* Diving instructor
* Introductory diving
* Low Impact Diver
* Master Instructor
* Master Scuba Diver
* Open Water Diver
* Rescue Diver
* Solo diver
* Supervised diver

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)
* Global Underwater Explorers (GUE)
* International Association of Nitrox and Technical Divers (IANTD)
* National Association of Underwater Instructors (NAUI)
* Professional Association of Diving Instructors (PADI)
* Professional Diving Instructors Corporation (PDIC)
* Technical Diving International (TDI)
* 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 (surface swimming & bi-fins)

|

Snorkeling/breath-hold|

* Spearfishing
* Underwater football
* Underwater hockey
* Underwater rugby
* Underwater target shooting

Breath-hold|

* Aquathlon (underwater wrestling)
* Apnoea finswimming
* Freediving
* Underwater ice hockey

Open Circuit Scuba|

* Immersion finswimming
* Sport diving (sport)
* Underwater orienteering
* Underwater photography (sport)

Rebreather|

* Underwater photography (sport)

Sports governing
organisations|

* International
* AIDA International
* Confédération Mondiale des Activités Subaquatiques)
* National
* Australian Underwater Federation
* 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)

Freediver Federations|

* AIDA International
* AIDA Hellas
* British Freediving Association (BFA)
* Confédération Mondiale des Activités Subaquatiques (CMAS)

Sports federations|

* Australian Underwater Federation (AUF)
* British Octopush Association (BOA)
* British Underwater Sports Association (BUSA)
* Federación Española de Actividades Subacuáticas (FEDAS)
* Fédération Française d'Études et de Sports Sous-Marins (FFESSM)
* South African Underwater Sports Federation (SAUSF)
* Türkiye Sualtı Sporları Federasyonu (TSSF)
* Underwater Society of America (USOA)

Underwater divers

| Pioneers of diving|

* Aquanaut
* Jacques Cousteau
* Hans Hass
* Arne Zetterström

|

Underwater scientists and archaeologists|

* 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
* David Gibbins
* Robert F. Marx
* Charles T. Meide
* Mark M. Newell
* John Peter Oleson
* Margaret Rule
* Gunter Schöbel
* E. Lee Spence
* Robert Sténuit
* Peter Throckmorton

Scuba record holders|

* Sheck Exley
* Nuno Gomes

Underwater filmmakers|

* Samir Alhafith
* David Attenborough
* Ramón Bravo
* 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 and Valerie Taylor
* Albert Tillman
* John Veltri
* Stan Waterman
* Jiang Wenhao
* Michele Westmorland
* John Ernest Williamson
* J. Lamar Worzel

Underwater explorers|

* Caves
* Sheck Exley
* Martyn Farr
* Jill Heinerth
* William Hogarth Main
* Rick Stanton
* Bill Stone
* John Volanthen
* Reefs
*   * Wrecks
* Clive Cussler
* Aristotelis Zervoudis

Science of underwater diving

| Diving
physics|

* Breathing performance of regulators
* Buoyancy
* Archimedes' principle
* Neutral buoyancy
* Diffusion
* Molecular diffusion
* Force
* Gas law
* Amontons's law
* Boyle's law
* Charles's law
* Combined gas law
* Dalton's law
* Gay-Lussac's law
* Ideal gas law
* Oxygen fraction
* Permeation
* Pressure
* Absolute pressure
* Ambient pressure
* Atmospheric pressure
* Gauge pressure
* Hydrostatic pressure
* Metre sea water
* Partial pressure
* Psychrometric constant
* Solubility
* Henry's law
* Saturation
* Solution
* Supersaturation
* Surface tension
* Hydrophobe
* Surfactant
* Torricellian chamber
* Underwater vision
* Snell's law
* Weight
* Apparent weight

|

Diving
physiology|

* Artificial gills
* Circulatory system
* Blood shift
* Patent foramen ovale
* Perfusion
* Systemic circulation
* Cold shock response
* Diving reflex
* Equivalent narcotic depth
* Lipid
* Maximum operating depth
* Metabolism
* Physiological response to water immersion
* Respiration
* Blood–air barrier
* Breathing
* CO₂ retention
* dead space
* Gas exchange
* Hypocapnia
* Normocapnia
* Respiratory exchange ratio
* Respiratory quotient
* Respiratory system
* Work of breathing
* Tissue
* Underwater vision

| 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
* Maximum operating depth
* Oxygen window in diving decompression
* Physiology of decompression
* Pulmonary circulation

|

Diving
environment|

| Diving
environment
classification|

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

|

Environmental
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
* List of diving hazards and precautions
* Reef
* Coral reef
* Stratification
* Thermocline
* Tides
* Turbidity
* Wind wave
* Breaking wave
* Surf
* Surge
* Wave shoaling

Special interest groups

* Artificial Reef Society of British Columbia (ARSBC)
* CMAS Europe
* Diving Equipment and Marketing Association (DEMA)
* Divers Alert Network (DAN)
* Green Fins
* Historical Diving Society
* Nautical Archaeology Society (NAS)
* Naval Air Command Sub Aqua Club
* Project AWARE
* Reef Life Survey
* Save Ontario Shipwrecks (SOS)
* SeaKeys
* Sea Research Society

Other

* Submarine escape training facility

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

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