[17] In January 2021 K2 became the final eight-thousander to be summited in the winter by a team of Nepalese climbers led by Nirmal Purja and Mingma Gyalje Sherpa.

Other local names have been suggested including Lamba Pahar ("Tall Mountain" in Urdu) and Dapsang, but these are not widely used.

The Italian climber Fosco Maraini argued in his account of the ascent of Gasherbrum IV that while the name of K2 owes its origin to chance, its clipped, impersonal nature is highly appropriate for such a remote and challenging mountain.

Melt waters from glaciers, such as those south and east of K2, feed agriculture in the valleys and contribute significantly to the regional fresh-water supply.

[31] A 1986 expedition led by George Wallerstein made an inaccurate measurement showing that K2 was taller than Mount Everest, and therefore the tallest mountain on Earth.

Near the memorial to the climbers who have died on K2, above Base Camp on the south spur, thin impure marbles with quartzites and mica schists, called the Gilkey-Puchoz sequence, are interbanded within the orthogneisses.

On the west face of Broad Peak and the south spur of K2, lamprophyre dikes, which consist of clinopyroxene and biotite-porphyritic vogesites and minettes, have intruded the K2 gneiss.

For example, a fault separates the K2 gneiss of the east face of K2 from limestones and slates comprising nearby Skyang Kangri.

[36][38] 40Ar/39Ar ages of 115 to 120 million years ago obtained from and geochemical analyses of the K2 Gneiss demonstrate that it is an older, metamorphosed, pre-collisional Cretaceous granite.

Later, the K2 Gneiss was then intruded by leucogranite dikes and finally exhumed and uplifted along major breakback thrust faults during post-Miocene time.

The K2 Gneiss was exposed as the entire K2-Broad Peak-Gasherbrum range experienced rapid uplift with which erosion rates have been unable to keep pace.

[41] The first serious attempt to climb K2 was undertaken in 1902 by Oscar Eckenstein, Aleister Crowley, Jules Jacot-Guillarmod, Heinrich Pfannl, Victor Wessely, and Guy Knowles via the Northeast Ridge.

[42] After five serious and costly attempts, the team reached 6,525 metres (21,407 ft)[43]—although considering the difficulty of the challenge, and the lack of modern climbing equipment or weatherproof fabrics, Crowley's statement that "neither man nor beast was injured" highlights the relative skill of the ascent.

The failures were also attributed to sickness (Crowley was suffering the residual effects of malaria), a combination of questionable physical training, personality conflicts, and poor weather conditions—of 68 days spent on K2 (at the time, the record for the longest time spent at such an altitude) only eight provided clear weather.

They concluded that the Abruzzi Spur was the most practical route and reached a height of around 8,000 meters (26,000 ft) before turning back due to diminishing supplies and the threat of bad weather.

The attempt failed after a storm pinned down the team for 10 days at 7,800 metres (25,590 ft), during which time climber Art Gilkey became critically ill. A desperate retreat followed, during which Pete Schoening saved almost the entire team during a mass fall (known simply as The Belay), and Gilkey was killed, either in an avalanche or in a deliberate attempt to avoid burdening his companions.

The expedition was led by Ardito Desio, and the two climbers who reached the summit were Lino Lacedelli and Achille Compagnoni.

The ascent is controversial because Lacedelli and Compagnoni established their camp at a higher elevation than originally agreed with Mehdi and Bonatti.

Efforts in the 1950s to suppress these facts to protect Lacedelli and Compagnoni's reputations as Italian national heroes were later brought to light.

[54] On 9 August 1977, 23 years after the Italian expedition, Ichiro Yoshizawa led the second successful ascent, with Ashraf Aman as the first native Pakistani climber.

This ascent was made by an American team, led by James Whittaker; the summit party was Louis Reichardt, Jim Wickwire, John Roskelley, and Rick Ridgeway.

Rakoncaj was a member of the 1983 Italian expedition led by Francesco Santon, which made the second successful ascent of the North Ridge (31 July 1983).

Three years later, on 5 July 1986, he reached the summit via the Abruzzi Spur (double with Broad Peak West Face solo) as a member of Agostino da Polenza's international expedition.

[108] The second challenge is the mountain’s tendency to experience extreme storms lasting several days, which have resulted in many of the deaths on the peak.

Above the Black Pyramid, the route continues along dangerously exposed and difficult-to-navigate slopes leading to the easily visible "Shoulder" and then on to the summit.

The last major obstacle is a narrow couloir known as the "Bottleneck", which places climbers dangerously close to a wall of seracs that form an ice cliff to the east of the summit.

It is rarely climbed, partly due to very difficult access, involving crossing the Shaksgam River, which is a hazardous undertaking.

This route, more technically difficult than the Abruzzi,[citation needed] ascends a long, steep, primarily rock ridge to high on the mountain—Camp IV, the "Eagle's Nest" at 7,900 metres (25,900 ft)—and then crosses a dangerously slide-prone hanging glacier by a leftward climbing traverse, to reach a snow couloir which accesses the summit.

In 2007, Denis Urubko and Serguey Samoilov intended to climb the K2's North Face but they were stymied by increasingly deteriorating conditions.

[127] Windy Gap is a 6,111-meter-high (20,049 ft) mountain pass 35°52′23″N 76°34′37″E / 35.87318°N 76.57692°E / 35.87318; 76.57692 at east of K2, north of Broad Peak, and south of Skyang Kangri.