The northwest coast of the peninsula is believed to have been mapped by the British navigator Edward Bransfield in Jan., 1820, and was explored by sealers in 1820-21. First considered to be part of the continent, the peninsula was later (1928) thought to be a group of islands; the John Rymill expedition (1934-37) proved its peninsularity. It was originally named Palmer Peninsula by Americans for Nathaniel Palmer, a U.S. captain who explored the area in Nov., 1820. In 1832, Britain claimed it and called it Graham Land and Trinity Peninsula. Argentina claimed it in 1940 as San Martin Land and Chile in 1942 as O'Higgins Land. In 1964, by international agreement, the entire feature was called the Antarctic Peninsula; Graham Land, Trinity Peninsula, and Palmer Land are used as local names.
The peninsula is now the site of numerous research stations. The disintegration of a Rhode Island-sized section of the Larsen ice shelf over a few weeks time in 2002, although directly due to locally warmer temperatures, was also regarded by some scientists as a result of the more general global warming. It was the largest of several ice shelves on the peninsula that have retreated since the 1960s.
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica, and almost the only part of that continent that extends outside the Antarctic Circle. It lies in the Western Hemisphere, facing South America, making it a part of West Antarctica. It extends from a line between Cape Adams (Weddell Sea) and a point on the mainland south of Eklund Islands, to Prime Head.
The Antarctic Peninsula is important because research has revealed that the forces of climate change are having a great effect on the region. The remote polar position has resulted in the area being dotted with numerous research stations and multiple claims of sovereignty. The peninsula forms part of claims by the Argentine Antarctica, British Antarctic Territory and Chilean Antarctic Territory although the exact boundaries of each claim are still disputed
Other portions of the peninsula that were named upon discovery include Bowman Coast, Black Coast, Danco Coast, Davis Coast, English Coast, Fallieres Coast, Loubet Land, Nordenskjold Coast and the Wilkins Coast.
The peninsula is highly mountainous, its highest peaks rising to approximately 2,800 metres (9,186 ft). Notable peaks on the peninsula include Mount Castro, Mount Coman, Mount Gilbert, Mount Jackson, Mount William, Mount Owen and Mount Scott. These mountains are considered to be a continuation of the Andes of South America, with a submarine spine connecting the two. That is an argument advanced by Chile and Argentina for their territorial claims.
The landscape of the peninsula is typical Antarctic tundra. The peninsula has a sharp elevation gradient, with glaciers flowing into the Larsen Ice Shelf, which experienced significant breakup in 2002. Other ice shelfs on the peninsular include George VI Ice Shelf, Wilkins Ice Shelf, Wordie Ice Shelf and the Bach Ice Shelf. The Filchner-Ronne Ice Shelf lies to the east of the peninsula.
Separating the peninsula from nearby islands is the Antarctic Sound, Erebus and Terror Gulf, George VI Sound, Gerlache Strait and the Lemaire Channel. Further to the west lies the Bellingshausen Sea and in the north is the Scotia Sea. The Antarctic Peninsula and Cape Horn create a funneling effect, which channels the winds into the relatively narrow Drake Passage. Hope Bay, at , is near to the northernmost extremity of the peninsula, which is Prime Head, at 63º13'S.