6.5 miles long. At 1961 terminus of Yakutat Glacier, 30 mi. SE of Yakutat Bay, St. Elias Mts.
Named by Blackwelder (1907, p. 424), U.S. Geological Survey (USGS), " * * * from the fact that a pair of harlequin ducks (Histrionicus histrionicus) were the only living things seen upon it." Also called Terminal Lake on a U.S. Geological Survey (USGS) manuscript map dated 1907.