Inaccessible Island is a volcanic island located in the South Atlantic Ocean, 31 km south-west of Tristan da Cunha. Its highest point, Swale's Fell, reaches 581 m, and the island is 12.65 km2 in area. The volcano was last active six million years ago and is currently extinct.
Inaccessible Island 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. Tristan da Cunha itself is accessible only by sea via a seven-day voyage from Cape Town, South Africa, and the harbour on Inaccessible Island allows access for only a few days of the year. Access to the island must be granted by the local government office.
Wikipedia https://en.wikipedia.org/wiki/Inaccessible_Island
Coordinates -37°18'9" N -12°40'27.998" E