STS038-086-104 Diego Garcia, Chagos Archipelago November 1990 The largest of the coral atolls of the Chagos Archipelago, Diego Garcia, is visible in this northwest-looking view. Diego Garcia is approximately 350 miles (560 km) south of the Maldive Islands in the central Indian Ocean. The crescent shape of the coral island encloses a lagoon that forms the harbor. Diego Garcia is the site of a large Anglo-American Naval Air and Communications facility located on the northwest part of the atoll.