A 1,300-kilometre finger of ice-covered bedrock islands
The Antarctic Peninsula, the northernmost reach of mainland Antarctica, juts 1,300 kilometres toward South America and covers 522,000 square kilometres, 80 per cent of it under ice. Chile calls it O'Higgins Land and Argentina Tierra de San Martín, yet beneath the ice it is really a string of bedrock islands.
Under the ice, the peninsula is a chain of bedrock islands divided by deep channels whose floors lie well below today's sea level, all bound together by grounded ice. Its mountains, topped by Mount Hope at 3,239 metres, are considered an extension of the Andes joined by a submarine ridge, an argument Chile and Argentina use in their claims. Argentina, Chile and Britain all claim overlapping parts; no claim is internationally recognised, and under the Antarctic Treaty System none is enforced.
The likeliest first sighting of any part of the Antarctic mainland came on 27 January 1820, when Bellingshausen's Russian expedition saw what it took for an ice field dotted with small hillocks. Three days later Edward Bransfield and William Smith charted the tip now called Trinity Peninsula, and John Biscoe named the northern section Graham Land in 1832. The sealer John Davis was almost certainly the first ashore, though sealers kept deliberately unreliable logs. Americans had called it Palmer Peninsula until a 1964 agreement settled on the present name.
Britain's wartime Operation Tabarin founded the first Antarctic research stations, and the 1950s brought a flurry of bases as Britain, Chile and Argentina competed over the same ground. With the mildest climate on the continent, the peninsula hosts the densest cluster of stations, among them Palmer, Rothera and Bellingshausen, and receives most of Antarctica's tour ships, many heading for the Lemaire Channel. In 1989 the Argentine vessel Bahía Paraíso ran aground nearby, spilling about 640,000 litres of oil.
Across the last half-century, the mild, damp sea-influenced weather once confined to the north of the western shelf has spread southward, displacing the cold, dry continental regime and shrinking sea ice. The Larsen Ice Shelf, fed by glaciers off the peninsula, broke up substantially in 2002. In March 2025 scientists described a thriving seafloor community, several species new to science among it, some 1,300 metres down where a Chicago-sized iceberg had split from the George VI Ice Shelf around 2020.
Source: Antarctic Peninsula
