Inaccessible Island is an extinct volcano (last active 6 million years ago) with Cairn Peak reaching 449 meters. The island is 14 km² (5.5 sq mi) in area, rising out of the South Atlantic Ocean 45 km (28 mi) southwest of Tristan da Cunha. Inaccessible Island is located at 37°18′9″S 12°40′28″WCoordinates: 37°18′9″S 12°40′28″W.
It is part of the archipelago of Tristan da Cunha, which is part of the overseas territory of the United Kingdom, known as Saint Helena, Ascension and Tristan da Cunha. Throughout its history it has had no permanent population and together with Gough Island is a protected wildlife reserve which has been designated a World Heritage Site by UNESCO.