Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around 1,600 kilometres (1,000 mi) from the coast of Africa and 2,250 kilometres (1,400 mi) from the coast of South America, which is roughly midway between the horn of South America and Africa. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around 1,300 kilometres (800 mi) to the southeast. The territory also includes the “remotest populated archipelago” on earth, the sparsely populated Tristan da Cunha archipelago, some thirty degrees farther south and about half the way to the Antarctic Circle.
The island is named after the day of its recorded discovery, Ascension Day, and is located at 7°56′S 14°22′W, about as far south of the equator as tropical Venezuela is to its north. Historically, it has played a role as an important safe haven and coaling station to mariners and for commercial airliners during the days of international air travel by flying boats and during World War II was an important naval and air station, especially providing antisubmarine warfare bases in the Battle of the Atlantic and throughout the war. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922.
The island is the location of RAF Ascension Island, which is a Royal Air Force station with a United States Air Force presence, a European Space Agency rocket tracking station, an Anglo-American signals intelligence facility and the BBC World Service Atlantic Relay Station. The island was used extensively by the British military during the Falklands War. Ascension Island hosts one of five ground antennae (others are on Kwajalein Island, Diego Garcia, Colorado Springs and Hawaii) that assist in the operation of the Global Positioning System (GPS) navigational system.