kotamadya (municipality), western Sumatera Utara (North Sumatra) provinsi (province), north-central Sumatra, Indonesia, located 130 miles (209 km) south of Medan, the provincial capital. A port on Sibolga Bay (an inlet of the Indian Ocean), it is linked by road with Tarutung and Pematangsiantar to the north and with Padangsidimpuan to the southeast. The city is protected by Mursala Island nearby to the southwest. The population is a mixture of Acehnese, Minangkabau, and coastal Malay, and a few Indians, Arabs, and Chinese, who are mostly traders.

The city is a centre of trade and transshipment; exports include rubber, coffee, timber, resin, camphor, and copra. Industries include sawmilling, weaving, wood carving, and mat and basket weaving. Deep-sea fishing is also important. A mosque is located in the city. Pop. (2000) 77,052; (2005 est.) 90,489.