Diego Garcia is the largest land mass in the Chagos Archipelago (which includes Peros Banhos, the Salomon Islands, the Three Brothers, the Egmont Islands, and the Great Chagos Bank), being an atoll occupying approximately , of which  is dry land. The continuous portion of the atoll rim stretches  from one end to the other, enclosing a lagoon  long and up to  wide, with a  pass opening at the north. Three small islands are located in the pass.