West Antarctica is the part of Antarctica that falls in the Western Hemisphere, west of the arbitrary line of 0^o longitude on the South America-facing side down to the South Pole then 180^o on the Australia-facing side. It's mostly a high, even plateau with an intensely cold dry climate and no wildlife, not even tundra. It contains the continent's highest point, Mount Vinson, and also its lowest, entombed somewhere below 3-4 km of ice.

As with the rest of the continent, this area is governed by the Antarctic Treaty, which seeks to protect the fragile environment, forbids military use, and sets aside national claims. Thus, various nations own and operate bases here and have hypothetical claims to territory which they waive. References to nations on this page should be understood accordingly. The unique feature of West Antarctica is that one large area, Marie Byrd Land, is so utterly desolate that no nation has ever sought to claim it.

It's believed that East Antarctica has been continuously ice-clad for 15 million years, while West Antarctica has repeatedly shed then regained its ice over climatic cycles. There are signs that it may be about to lose its ice again, with global repercussions. The cause is not air temperature, which remains way below freezing, but warmer ocean water seeping beneath the glaciers to warm them, salt them, and lubricate their flow. Other factors in the mix are ozone depletion and volcanic hot spots. The area is therefore of great importance to climate science.

Regions

• The South Pole is in neither the eastern nor western hemisphere - or alternatively it's in both - and is described separately.
• The Antarctic Peninsula and most of the Antarctic Islands lie in the western hemisphere but are described separately as they're different in climate and character. They're often visited by cruise ships.
• Ellsworth Land is the region south of the Peninsula, bounded by the Bellingshausen Sea. The mountains of the Peninsula here merge into the plateau, then re-emerge to form the 360 km chain of the Ellsworth Mountains, bisected by the Minnesota Glacier. The northern part or Sentinel Range has Antarctica's highest mountains, the Vinson Massif, peaking at 4892 m Mount Vinson. In the southern part, the Heritage Range, are Union Glacier Station (Chile, summer) and the privately-run Union Glacier Camp: this has an airstrip and organises trips and supplies to the interior and the annual Ice Marathon.
• Marie Byrd Land is the large pie-segment of Antarctica west of Ellsworth Land and east of the Ross Sea that is mostly terra nullius - no nation has thought it worth claiming. There are no bases: the former Soviet Russkaya Station closed in 1990, and the US Byrd Station closed in 2005. The lowest point on earth not covered by sea lies somewhere beneath its thick ice. This ice flows north into the Amundsen Sea, where it forms a sheet the size of Texas and 3 km thick. One especially fast-flowing component is the Thwaites Glacier, galloping along at 2 km a year and protruding out to sea as a long tongue - its dynamics are crucial to predictions about climate change and ocean rise.
• Edith Ronne Land is the unofficial name for the area south of the Weddell Sea, with the Pensacola Mountains running through it. In 2012 the UK government declared it to be "Queen Elizabeth Land", drawing predictable ripostes from other Treaty nations. There are no bases.
• Coats Land is the region east of the Peninsula, bounded further east by Queen Maud Land in East Antarctica. (Some definitions follow the geography rather than the longitude, and consider Coats Land to be in East Antarctica.) To the north is the Weddell Sea, mostly covered by the huge Filchner-Ronne Ice Shelf: fragments that break from this can be the size of whole counties, and persist as icebergs all the way to New Zealand. Bases in Coats Land are Belgrano II (Argentina), Halley VI (UK), Neumayer III (Germany) and SANAE IV (South Africa).
• The Ross Sea is bisected by the 180^o line. It's a major hub for transport towards the pole, often visited by cruises from Australia and New Zealand, and is described separately.

Get in

• Ice breakers bring the heavy supplies to the coastal bases. They only come in annually in mid-summer, are hurriedly unloaded then retreat north before the Weddell Sea ice traps them. So if you come that way it's either a very short or a very long stay.
• Otherwise, you have to fly. And inland places can't be reached by ship.
• 1 Union Glacier Blue-Ice Runway and Camp in Ellsworth Land is operated by Antarctic Logistics & Expeditions (ALE), a private company supporting scientific, expedition and leisure activity on the continent. The runway is natural glacier "blue ice" not packed snow as the climate is so dry, which means that conventional wheeled aircraft can land here - these can carry much more weight and operate over greater range than ski-planes. This enables ALE to fly passengers and cargo here from Punta Arenas once a week from Nov-Jan, using an Ilyushin IL-76 TD jet. The 3000 km flight takes just over four hours.
• 2 Thiel Mountains has a fuel cache for aircraft flying between Union Glacier Camp and the South Pole, a 1138 km haul. It might save your life but that's all there is, there's no base here.

Get around

Transport close to the bases is on foot, skis, skidoos or tractors. Light aircraft venture further out.

Bases

The higher the base number, the more challenging the conditions, because it indicates how many previous bases have succumbed to the ice.

• 1 Belgrano II Base (Argentina) is perched on the tiny Bertrab Nunatak, so it's on solid rock not on shifting ice. It was badly damaged by fire in 2005 but rebuilt by 2010. Tunnelled out of the ice is the world's southernmost church, and a historic cross stands on the rock. The base is mostly supplied by an icebreaker, but there's a year-round ice airstrip 2 km away, and supplies can be supplemented by air-drop, as they were during the rebuilding. The base, opened in 1979, replaced Belgrano I (1955-1979) which was out on the ice, and it has long outlasted Belgrano III (1980-84) on the same unstable site. Along the coast are two Argentinian refuges, Cisterna and Zapiola.

Building Halley VI

• 2 Halley VI Research Station (UK) is named for the astronomer who identified Halley's Comet. There's been a base hereabouts since 1956, mainly studying the atmosphere, but it's out on the Brunt ice shelf so four previous stations were destroyed. The fifth, becoming unsafe, was cannibalised for the present sixth station, operational from 2012. This is a remarkable structure of eight modules set on gigantic retractable skis, a hybrid of freight train, colossal caterpillar, and Howl's Moving Castle. In 2016 cracking of the ice prompted a move 23 km further in, bringing it within 20 km of the mainland coast (where glaciers cascade over cliffs to form the Brunt Icefall). In spite of this, cracking remains a concern, and the base has not been staffed over winter since that time. Its main supply is by icebreaker, supplemented by flights to the base air strip.
• 3 Neumayer-Station III (Germany), opened in 2009, is named for the geophysicist and explorer who was an early proponent of international scientific cooperation. It's in Atka Bay on the Ekström Ice Shelf, 6 km south of the abandoned Neumayer II (1993-2009) which became buried in snow, as did Neumayer I (1981-1992). The station is fixed on stilts so it can be periodically raised, though it continues to move towards the ice edge at 160 m / year.
• 4 SANAE IV (South Africa) is perched on the flat-topped Vesleskarvet Nunatak in Queen Maud Land - so it's in East Antarctica but is convenient to describe here. Its three predecessors became buried on the Fimbul Ice Sheet, but its stilts and position near a cliff edge mean that snow blows away instead of accumulating. Built of three double-decker modules and opened in 1997, it has far exceeded its designed life expectancy. It's supplied by the icebreaker S.A Agulhas II, which doubles as a research vessel in its own right.

See and Do

• Check the suggestions for Antarctica#See_and_Do. The most important thing for you to do here is come home safe.
• Nunataks: most of Antarctica is very thick ice, continually moving. Anything built on the ice eventually gets crushed or cracked apart, or finds itself on a cast-off ice floe drifting and shrinking out to sea. A nunatak is an isolated mountain or similar outcrop protruding from the ice (whether land-ice or permanent sea-ice). In the Arctic these may develop unique island habitats; continental Antarctica is generally too cold for that but they're one of the few places that reveal the underlying geology.
• 1 Marie Byrd Land: nothing to see on the surface of this frozen plateau, but beneath it are the lowest places on earth not covered by ocean. They're pressed down by the weight of 3-4 km thickness of ice, buckling the earth's crust and somewhat impeding measurement, but the lowest point had been reckoned to be the Bentley Subglacial Trench, 2555 m or 8382 ft below sea level. It's separated by a subglacial ridge from the Byrd Subglacial Basin, and a 2013 survey put this even deeper, at minus 2870 m.

Summit of Mount Vinson

• 2 Mount Vinson (Vinson Massif). The highest peak in Antarctica, standing at 4892 m (16,050 ft). Climbs can be arranged by specialist agencies such as RMI and Adventure Consultants for some tens of thousands of US$ per person, and they take 14+ days round trip from Punta Arenas. Of the "seven summits" - the highest peaks on all seven continents - Vinson and Everest are rated the hardest. Vinson is much lower than Everest, so you spend little time in the "death zone" above 4000 m, and the climb is less technically demanding, but it's the remoteness and literally perishing cold that create the challenge. (updated Feb 2020)
• Mount Tyree 13 km north of Vinson, is Antarctica's second highest peak at 4852 m (15,919 ft). So it forms one of the "second seven", which some mountaineers reckon to be more difficult than the "seven summits." As of 2020, only 15 people have reached the summit of Mount Tyree, and the 2000 m ice wall of its southern face has not yet been climbed.
• 3 Mount Sidley is Antarctica's highest volcano, at 4181 m (13,717 ft). So it forms part of the "seven volcanoes" climbing challenge similar to the "seven summits". It's extinct, but as with Vinson and Tyree it's the remoteness and extreme cold that mean few have climbed it.
• Antarctic Ice Marathon, ow@icemarathon.com. This will be staged at Union Glacier Camp in Ellsworth Land (see "Get in") on 13 Dec 2020; the fee includes flights to and from Punta Arenas. The full marathon is two laps, with a half marathon option of one lap. And that's only the start of the World Marathon Challenge, to complete 7 Marathons on 7 continents in 7 days. (So the next six are Cape Town, Perth in Western Australia, Dubai, Madrid, Fortaleza in Brazil, and Miami.) Registration for 2020 is full but you can apply for the waiting list. Registration for 2021 is open, and it's to be held at the same location on 13 Dec 2021. Fee $18900 for 2020. (updated Feb 2020)
• The total solar eclipse on Saturday 4 Dec 2021 crosses this area but will be extremely difficult to view, as it's over the most remote areas. It arrives across the Weddell Sea to reach Edith Ronne Land at 07:30. Here it becomes an unusual example of a westbound eclipse because of the earth's tilt, crossing the continent via the Vinson Massif of Ellsworth Land into Marie Byrd Land, then north into the Amundsen Sea to end at 08:00. The bases in this region will see a high-partial eclipse but miss totality.
• No penguins unless someone's brought a woolly mascot: they need access to an unfrozen sea. The plateau is too remote and too cold even for penguins - think carefully about that before planning to come here.

Eat

Like anywhere else in Antarctica, food will be served in bases, and must be carried when outside bases.

Drink

"Water, water everywhere yet not a drop to drink:" you are surrounded by freshwater ice that is deep-deep-frozen. Bases can melt it but equipment to do so in bulk is heavy and needs fuel. So on extended trips away from base, this adds weight, and lugging weight raises a thirst.

Sleep

This is not the place for wild camping. You (or your trip organiser) must negotiate access to a base, or bring a heavy-duty self-sufficient expedition.

They say Antarctica is cold ^{[citation needed]}, but that is nothing compared to the chill you'll encounter if you just turn up asking for shelter. Every few years, some larrikin thinks it great sport to load up a Cessna with a thermos flask and an extra pullover and try to fly to the South Pole. Some realise their folly and turn back in time to reach safety, some flop in the ocean and vanish, some flop in East Antarctica and some in West. The answer's the same: sorry mate.

Stay safe

West Antarctica is extremely cold and remote, and medical care on the bases is limited. Travel / health insurance that covers a cruise trip to the Peninsula will not be valid for the hazards involved in visiting this region, eg to participate in the Ice Marathon or climb Vinson. The cost of a medical evacuation would be huge.

Go next

The problem is that you can only get here on specialist round trips, with no onward options. Reaching anywhere else in Antarctica (even within West Antarctica) might mean doubling back via South America. Ask ahead about cross-country supply flights that might connect you to another base.