Diomede Islands, two rocky islands, Bering Strait, about halfway between Alaska and Siberia. They were reached about 1728 by the Danish explorer Vitus Bering. Little Diomede (6 sq km/2 sq mi) belongs to the United States, and Big Diomede or Ratmanov (29 sq km/ 11 sq mi) to Russia. The islands are 4 km (2.5 mi) apart and lack harbor facilities. Between them runs the international date line, part of which forms the boundary between Russia and the U.S. Fewer than 100 Eskimos are said to inhabit the islands.