Tiwi Islands, island group, Northern Territory, Australia, c.50 mi (80 km) N of Darwin, in the Timor Sea. Consisting of Bathurst Island and the much larger Melville Island to the east across the narrow Apsley Strait, the group is separated from the Australian mainland by the Beagle Gulf (SW), Clarence Strait (S), Van Dieman Gulf (SE), and Dundas Strait (NE). The islands are named for the Tiwis, the aboriginal people who live there. Nguiu, on the southeastern tip of Bathurst, is the main township. The largely traditional economy is based on hunting, fishing, native arts and crafts, and some limited tourism.