Belgian naval officer who led the first Antarctic expedition concentrating on scientific observation (1897–99). Sailing with him as mate on the Belgica was Roald Amundsen (Amundsen, Roald), who on a subsequent expedition of his own was the first to reach the South Pole.

After making discoveries north of Graham (Palmer) Land, de Gerlache navigated the Belgica into the pack ice, where it remained trapped for 13 months and thus became the first vessel to winter in the Antarctic.

He sailed to the Persian Gulf to collect zoological specimens (1901). He also conducted oceanographic studies—off the east coast of Greenland (1905), north of Scandinavia and Russia in the Barents and Kara seas (1907), and in the Barents and Greenland seas (1909). De Gerlache made an overland crossing of Greenland from west to east at 77° N in 1909. He assisted the English explorer Sir Ernest Shackleton in planning the British Imperial Trans-Antarctic Expedition of 1914 to 1917.