Antarctic Peninsula, a long, narrow arm of Antarctica. It stretches generally northward for nearly 1,200 miles (1,900 km), reaching beyond the Antarctic Circle to within 650 miles (1,050 km) of the southern tip of South America. The peninsula is bounded on the west by the South Pacific Ocean, on the north by the Drake Passage, and on the east by the Weddell Sea, an arm of the South Atlantic Ocean. Most of the peninsula is mountainous, with peaks protruding above an immensely thick cover of ice. The northern coastal areas and nearby islands have the most moderate climate in Antarctica. Numerous research stations are located there.

For many years the peninsula was called by two names—Palmer Peninsula by the United States and Graham Land by Great Britain. In 1964 the two countries agreed upon a name—Antarctic Peninsula; the northern half is called Graham Land, the southern Palmer Land. Argentina, Chile, and Great Britain claim the peninsula. Under the terms of the Antarctic Treaty of 1959, these claims, like those for the rest of Antarctica, are being held in abeyance.