Part of the Indian Ocean .
Occupying about 839,000 sq mi (2,172,000 sq km), it is bordered by Sri Lanka, India, Bangladesh, Myanmar, and the northern Malay Peninsula . It is about 1,000 mi (1,600 km) wide, with an average depth of more than 8,500 ft (2,600 m). Many large rivers, including the Godavari, Krishna, Kaveri, Ganges, and Brahmaputra, flow into it. The Andaman and Nicobar Islands , the bay's only islands, separate it from the Andaman Sea . It has long been crossed by Indian and Malaysian traders; Chinese maritime trading dates from the 12th century. Vasco da Gama led the first European voyage into the bay in 1498.