Sumatra, second-largest island of Indonesia, about 183,000 sq mi (473,970 sq km) in area. Lying on the equator, with a hot, wet climate, Sumatra is heavily forested and rich in oil, bauxite, and coal; it produces 70% of Indonesia's export wealth. Crops include rubber, coffee, pepper, and tobacco. Medan and Palembang are the chief cities.
See also: Indonesia.