island, southwestern Sulu Sea, Philippines. Low-lying and surrounded by 13 small islets and coral reefs, Cagayan Sulu was a centre of pirate activity by Muslims (Moros) in the 19th century. The island (together with Sibutu island) was inadvertently omitted when the United States acquired the Philippine islands from Spain in 1898. Cagayan Sulu was later purchased from Spain in 1900 and was part of the Philippines when independence was granted in 1935. Dry-rice agriculture, copra production, and trading are the principal economic activities. The Samalan-speaking Jama Mapun people inhabit the island; they are Christians. Area 26 square miles (67 square km).