Buka Island, island of Papua New Guinea in the Solomon Sea, southwestern Pacific Ocean. Geographically, Buka is one of the northern Solomon Islands and lies northwest of Bougainville Island, from which it is separated by the deep, narrow Buka Passage, which ranges from about 980 to 3,500 feet (300 to 1,070 metres) wide. With Bougainville and several island groups, it forms the autonomous region of Bougainville. A volcanic formation measuring 35 miles by 9 miles (56 km by 14 km), Buka has a total land area of 190 square miles (492 square km). Rising to 1,634 feet (498 metres) in hills on the southwest, the island is densely forested in the interior. Rainfall is abundant, with more than 100 inches (2,500 mm) annually. Coral reefs fringe the south and west coasts, the latter deeply indented by Queen Carola Harbour.
Archaeological evidence shows that Buka has been occupied for at least 28,000 years. The island was visited in 1767 by a British navigator, Philip Carteret, who named it Winchelsea. Placed under a German protectorate in 1885, the island remained under that administration by virtue of a British-American-German agreement reached just before the turn of the century. The island was taken by Australian troops in 1914 and mandated to Australia in 1920. It was held by the Japanese from 1942 to 1945, was included in the UN Trust Territory of New Guinea after World War II, and became part of Papua New Guinea when that country achieved its independence in 1975. With Bougainville Island and several small island groups, Buka formed the North Solomons province (renamed Bougainville province in 1997).
In 1988 rebels seeking Bougainville’s independence from Papua New Guinea mounted an insurrection, and in 1990 Buka became the scene of violent clashes. In 2001 a peace agreement was reached, and in 2005 Bougainville and Buka, as well as several nearby islands, officially became an autonomous region. Buka, which had been the provincial headquarters since 1997, became the region’s administrative centre.