Saint Helena is a volcanic tropical island located in the South Atlantic Ocean, west of Africa. The nearest countries geographically are Angola and Namibia. The island is about 1,950 km (1,210 mi) west of Angola, and 4,000 km (2,500 mi) east of Rio de Janeiro, Brazil. It is one of the three constituent parts of Saint Helena, Ascension and Tristan da Cunha, a British overseas territory.