island marking the northeastern corner of Hauraki Gulf, eastern North Island, New Zealand. Separated from the Coromandel Peninsula (south) by Colville Channel, it is the largest island off North Island, with a total land area of 110 square miles (285 square km). Its mountainous surface rises to volcanic Mount Hobson (Hirakimata), 2,038 feet (621 m).

Known to the Maoris as Aotea, the island was named by Captain James Cook (1769). Earlier mining has been replaced by sheep and dairy farming. Now chiefly used as a summer resort, Great Barrier Island is accessible by launch from Auckland (55 miles 【88 km】 southwest) to Tryphena, on the south coast, and Port Fitzroy, on the west.