South Shetland Islands, archipelago in the Southern Ocean southeast of Cape Horn, the southernmost point of South America, and off the tip of the Antarctic Peninsula. Among the larger islands are Deception, Elephant, and King George. The islands, mountainous, snow-covered, and uninhabited, were sighted in 1819 by a British mariner and were subsequently claimed by Britain. In 1962 the archipelago was made a part of the British Antarctic Territory, but the claim has been disputed by Chile and Argentina. Area, 4,700 sq km (1,800 sq mi).