Diego Garcia is an atoll located in the heart of the Indian Ocean, some 1,600 km (1,000 mi) south off India's and Sri Lanka's southern coast. Diego Garcia is the largest atoll by land area of the Chagos Archipelago. It is part of the British Indian Ocean Territory (BIOT), a British overseas territory.
Since the enforced depopulation of Diego Garcia in the years leading up to 1973, it has been used as a military base by the United Kingdom and the United States. Diego Garcia along with Kwajalein and Ascension Island each host one of the three ground antennas to assist in the operation of the Global Positioning System.
The atoll is now covered in luxuriant tropical vegetation, with little sign left of the copra and coconut plantations that once covered it. The island is long, with a maximum elevation of , and nearly encloses a lagoon some long and up to wide. Depths in the lagoon extend to , while numerous coral heads extend toward the surface and form hazards to navigation. Shallow reefs surround the island on the ocean side as well as within the lagoon. The channel and anchorage area are dredged, while the old turning basin can also be used if its depth is sufficient for the ship.
