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 less than half are inhabited. The islands are governed as a part of North Sumatra province. In Indonesian and Malay, batu means rock or stone. Sumatra (also spelled Sumatara and Sumatera) is the sixth largest island of the world (approximately 470,000 km²) and is the largest part of Indonesia. ... Pulau Nias, off Sumatra, Indonesia Nias (Indonesian: Pulau Nias, Nias language: Tanö Niha) is an island off the western coast of Sumatra, Indonesia. ... Sumatra Siberut is one of the Mentawai Islands, lying west of Sumatra in the Indian Ocean. ... Map of North Sumatra province within Indonesia North Sumatra (Indonesian: Sumatera Utara) is one of the provinces of Indonesia. ... The Malay language, also known locally as Bahasa Melayu, is an Austronesian language spoken by the Malay people who are native to the Malay peninsula, southern Thailand, Singapore, central eastern Sumatra, the Riau islands, and parts of the coast of Borneo. ...

The people of the Batu Islands have had substantial interaction with the populations of Nias, to the north. The islands have occasionally been a destination for slaves who escaped from Nias. The Buxton Memorial Fountain, designed by Samuel Sanders Teulon, celebrating the emancipation of slaves in the British Empire in 1834, erected in Victoria Tower Gardens, Millbank, Westminster, London. ...

The equator passes through the archipelago, north of Tanahmasa and south of Pini. The equator is an imaginary circle drawn around a planet at a distance halfway between the poles. ...