USFS Eider was an American motor schooner in commission in the fleet of the United States Bureau of Fisheries from 1919 to 1940 and, as US FWS Eider, in the fleet of the U.S. Fish and Wildlife Service from 1940 to 1942 and again in the late 1940s. She ran a passenger-cargo service between Unalaska and the Pribilof Islands, and also carried passengers, supplies, and provisions to destinations on the mainland of the Territory of Alaska and in the Aleutian Islands. She occasionally supported research activities in Alaskan waters and the North Pacific Ocean, and she conducted patrols to protect Alaskan fisheries and marine mammals. In 1924, she provided logistical support to the first aerial circumnavigation of the world.