Norwegian polar explorer, born in Borge, and educated at the University of Christiania (now the University of Oslo). He entered the Norwegian navy in 1894 and spent the following nine years studying science. From 1903 to 1906 he led his first important expedition in the small sloop Gjöa. During this voyage he sailed successfully through the Northwest Passage from the Atlantic to the Pacific Ocean and determined the position of the north magnetic pole. His next expedition (1910-12) sailed in a larger ship, the Fram, and gained fame as one of the most successful undertakings in the history of Antarctic exploration. With his companions, he lived in Antarctica for more than a year, conducting explorations and scientific investigations. On December 14, 1911, he reached the South Pole, becoming the first person known to have accomplished this feat. He had favorable weather conditions during the voyages, but his success was due primarily to his knowledge of polar conditions, his attention to minute details, and his ability to endure great physical stress.
Amundsen's plans for an expedition into the north polar regions were interrupted by the outbreak of World War I; in 1918, however, he sailed from Norway in an attempt to drift eastward across the North Pole with the ice currents of the Arctic Ocean. The currents proved too variable to permit a crossing of the pole, and he was forced to follow a more southerly route through the Northeast Passage along the northern coast of Europe and Asia. The voyage ended in 1920, when he arrived in Nome, Alaska. In 1922 another attempt to reach the pole by both ship and airplane failed, and in 1924 Amundsen came to the United States to raise funds for further expeditions. In May 1926 he succeeded in crossing the North Pole during a flight of more than 70 hours from Spitsbergen (Svalbard), Norway, to Teller, Alaska; he was accompanied by the American explorer Lincoln Ellsworth and the Italian explorer and engineer Umberto Nobile. This flight was made in the dirigible Norge, designed and built by Nobile with the support of the Italian government. Nobile and Amundsen subsequently quarreled, each claiming that the credit for the flight belonged to his respective country. In 1928, however, when Nobile's airship Italia was wrecked during a polar flight, Amundsen, who had retired, volunteered to search for him.