Born in Borge, Østfold, Norway, Amundsen began his career as a polar explorer as first mate on Adrien de Gerlache's Belgian Antarctic Expedition of 1897–1899. From 1903 to 1906, he led the first expedition to successfully traverse the Northwest Passage on the sloop "Gjøa". In 1909, Amundsen began planning for a South Pole expedition. He left Norway in June 1910 on the ship "Fram" and reached Antarctica in January 1911. His party established a camp at the Bay of Whales and a series of supply depots on the Barrier (now known as the Ross Ice Shelf) before setting out for the pole in October. The party of five, led by Amundsen, became the first to successfully reach the South Pole on 14 December 1911.