Tristan da Cunha, colloquially simply Tristan, is a constituent part of Saint Helena, Ascension and Tristan da Cunha comprising a remote group of volcanic islands in the south Atlantic Ocean. It is the most remote inhabited archipelago in the world, lying approximately 2,787 km off the coast of Cape Town in South Africa, 2,437 km from Saint Helena and 4,002 km off the coast of the Falkland Islands. The territory consists of the inhabited island, Tristan da Cunha, which has a diameter of roughly 11 kilometres and an area of 98 square kilometres; the wildlife reserves of Gough Island and Inaccessible Island; and the smaller, uninhabited Nightingale Islands. As of October 2018, the main island has 250 permanent inhabitants, who all carry British Overseas Territories citizenship. The other islands are uninhabited, except for the South African personnel of a weather station on Gough Island.
The head of state, as for all overseas territories, is the British monarch. The King's role in the territories is in his role as King of the United Kingdom, and not in right of each territory separately.
King Charles III acceded to the throne on 8 September 2022 upon the death of his mother, Queen Elizabeth II.