a group of islands located between the islands of Borneo and Mindanao; part of the Philippines. Population, 427,000 (1970). The Sulu Archipelago covers an area of 2,688 sq km. It extends 335 km from southwest to northeast and forms two chains and 13 island groups, including about 400 islands and reefs. The largest islands are Jolo and Tawi-Tawi. The larger islands are composed mainly of crystalline rocks; the smaller islands are coralline. The highest elevation is 790 m, on Jolo Island. The climate is humid equatorial; precipitation ranges from 2,000 to 3,200 mm per year. The islands have tropical forests. Rice, corn, and coconuts are the main crops. The population also engages in fishing and pearl diving. The capital is the town of Jolo.