The Tristan da Cunha group includes four islands; Tristan itself with its near neighbours Nightingale and Inaccessible, and Gough Island which lies 230 miles to the S.S.E. The group was discovered by Portuguese seamen in the early sixteenth century, but permanent occupation did not begin until 1810, when a small settlement was founded on Tristan. The Tristan Islanders, who now number over 250, have visited Nightingale and Inaccessible Islands regularly,% but Gough remained little visited and practically unknown until the South African Tristan da Cunha Expedition went there in 1948. As a result of this expedition the Tristan da Cunha Development Company was founded and a few years later they commenced regular exploitation of the crawfish around the coasts. In 1955 the Gough Island Scientific Survey took up residence in The Glen, Gough Island, and their hut now forms the nucleus of a South African Weather Station.