The island of Tristan da Cunha is located in the southern
Atlantic Ocean—more than 3,700 kilometers (2,300 miles) from the
coastline of Antarctica, approximately 2,800 kilometers (1,700
miles) to the southern tip of Africa, and more than 3,000
kilometers (1,900 miles) from the east coast of South America.
The island forms part of the British Overseas Territory of Saint
Helena, Ascension, and Tristan da Cunha. The shoreline of the 13
kilometer (8 mile) wide island is marked on most sides by steep
cliffs, with lower beach areas on the southern and north-
northwestern sides. The island is notable for its bird
population and includes important breeding grounds for petrels,
albatrosses, penguins, and shearwaters. Tristan da Cunha is a
shield volcano, a volcanic structure with a low, broad profile
and composed of silica-poor lavas (such as basalt). The upper
surface of this low base appears dark green in this astronaut
photograph. Steeper brown to tan colored slopes mark the central
cone of the volcano at the island