Map of the island of Ascension from Charles Darwin's Geological observations on the volcanic islands and parts of South America visited during the voyage of H.M.S. 'Beagle'. 2d edition. London: Smith Elder and Co., 1876. Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around 1,600 kilometres (1,000 mi) from the coast of Africa and 2,250 kilometres (1,400 mi) from the coast of South America, which is roughly midway between the horn of South America and Africa. This image has been color enhanced.