San FERNANDO, a seaport of southern Spain, in the province of Cadiz, on the Isla de Leon, a rocky island among the salt marshes which line the southern shore of Cadiz Bay. Pop. (1900), 29,635. San Fernando is one of the three principal naval ports of Spain; together with Ferrol and Cartagena it is governed by an admiral who has the distinctive title of captaingeneral. The town is connected with Cadiz (41 m. N.W.) by a railway, and there is an electric tramway from the arsenal (in the suburb of La Carraca) to Cadiz. The principal buildings are government workshops for the navy, barracks, a naval academy, observatory, hospital, bull-ring and a handsome town hall. In the neighbourhood salt in largely produced and stone is quarried; the manufactures include spirits, beer, leather, esparto fabrics, soap, hats, sails and ropes; and there is a large iron-foundry.
San Fernando was probably a Carthaginian settlement. On a hill to the S. stood a temple dedicated to the Tyrian Hercules; to the E. is a Roman bridge, rebuilt in the 15th century after partial demolition by the Moors. The arsenal was founded in 1790. During the Peninsular War the cortes met at San Fernando (1810), but the present name of the town dates only from 1813; it was previously known as Isla de Leon.