polar region, area around the North Pole or the South Pole. The northern polar region consists mainly of floating and pack ice, 7–10 feet (2–3 m) thick, floating on the Arctic Ocean and surrounded by land masses. The ice cap of the southern polar region averages 6,700 feet (about 2,000 m) in thickness, is underlaid by the continental landmass of Antarctica, and is surrounded by oceans. Both were first penetrated as far as the poles in the early 20th century—the North Pole in 1909 by Robert Peary and the South Pole in 1911 by Roald Amundsen.