Bougainville Island (Tok Pisin: Bogenvil) is the main island of the Autonomous Region of Bougainville of Papua New Guinea. It formed the main landmass of the German Empire-associated North Solomons. With four to five hundred-metre-width-strait separated Buka Island (c.500 km2) its land measures 9,300 km2 (3591 sq miles). The population of the province is 234,280 (2011 census), which includes islets such as the Carterets. Mount Balbi on the main island at 2,715 m is the highest point. The Buka strait, despite its narrowness, is unbridged; however, regular ferries operate between the key settlements on either side and Buka Town has the main northern airstrip/airport.