island and municipio especial (special municipality) of Cuba, in the Caribbean Sea. It is bounded on the northwest by the Canal de los Indios and on the north and northeast by the Gulf of Batabanó, which separate it from the mainland of Cuba. A 1904 treaty recognizing Cuba's sovereignty over the island was finally ratified by the United States in 1925. The island's present name was designated in 1978. With an area of 850 square miles (2,200 square km), it is the largest member of the Canarreos Archipelago. The northern part of the island is an undulating plain of pine forests and savannas, of sandy and rocky soils, with a few low mountains up to 944 feet (303 m) elevation. The main activities are fishing, truck farming, and citrus growing; grapefruit production predominates and is the basis for the economy of the island. The National Reformatory, a prison, is located a few miles from the island's capital and main town, Nueva Gerona. The section south of Lanier Swamp is small, rocky, and isolated, inhabited only by a few fishermen and charcoal makers. Kaolin and marble are extracted on the island. Pop. (2002) 86,557.