Biliran has a total land area of 536.01 square kilometres (206.95 sq mi), making it the fourth smallest province in the Philippines. The island lies off the northern coast of Leyte island across Biliran Strait. To the southeast is Carigara Bay, to the northeast is the Samar Sea, and across this sea is Samar. To the west is the Visayan Sea and Masbate lies 30 kilometres (19 mi) to the northwest. The province is composed of two major volcanic islands: the main island also named Biliran and Maripipi, a smaller island to the northwest. Other smaller islands include Higatangan and Dalutan.
The economy of Biliran is largely based on fishing. Most of its towns, especially Naval and Biliran, have excellent seaports. There are 95 hectares (230 acres) of brackish water fish ponds which produce prawns, shrimps and milkfish. Another 30 hectares (74 acres) of seawater are suitable for seaweed farming and 10 more hectares for fishcage culture. The principal raw material produced is copra and coconut oil. Processed goods include white clay ceramics, dried fish, raw gulaman, and citronella oil. The untapped natural resources of the island include geothermal power and the abundant sulfur and gypsum deposits.