The Batu Islands are an archipelago of Indonesia located in the Indian Ocean off the west coast of Sumatra, between Nias and Siberut. The three primary islands, of approximately equal size, are Pini, Tanahmasa, and Tanahbala. There are forty-eight smaller islands, of which the largest are Sipika, Simuk, Bodjo, Telo and Sigata; less than half are inhabited. The islands are governed as a part of South Nias regency within North Sumatra province.