Roald Amundsen, arctic explorer (b at Sarpsborg, Norway 16 July 1872; d between Norway and Spitsbergen 18 June 1928). Amundsen went to sea as a young man. Determined to navigate the NORTHWEST PASSAGE, he purchased the Gjoa, readied it for arctic waters and embarked in 1903. After 2 icebound winters, Gjoa emerged in the Beaufort Sea, the first ship to cross the top of North America. In 1911 Amundsen reached the South Pole and in 1920 he sailed through the Northeast Passage. Then he turned his attention to air exploration and in 1926 flew over the North Pole in an airship piloted by Umberto Nobile. Amundsen disappeared in 1928 on his way to search for Nobile, missing on another arctic flight.