Cho Oyu

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Lore & Background

Cho Oyu was first summited in the summer season, as were all 14 eight-thousanders from 1950 to 1964. The first winter ascent of an eight-thousander was by a Polish team led by Andrzej Zawada on Mount Everest, with Leszek Cichy and Krzysztof Wielicki reaching the summit on 17 February 1980; all-Polish teams would complete nine of the first fourteen winter ascents of eight-thousanders. Polish climber Maciej Berbeka made the first winter ascent of three eight-thousanders, including Cho Oyu, Manaslu, and Broad Peak. The first person to summit all 14 eight-thousanders was the Italian climber Reinhold Messner in 1986, who did not use any supplementary oxygen. In 2010, Edurne Pasaban, a Basque Spanish mountaineer, became the first woman to summit all 14 eight-thousanders, though with the aid of supplementary oxygen. In 2011, Austrian Gerlinde Kaltenbrunner became the first woman to summit all 14 eight-thousanders without the aid of supplementary oxygen. In 2013, South Korean Kim Chang-ho set a speed record by climbing all 14 eight-thousanders in 7 years and 310 days, without the aid of supplementary oxygen. In July 2023, Kristin Harila and Tenjen Lama Sherpa set a speed record of 92 days for climbing all 14 eight-thousanders, with supplementary oxygen. In July 2022, Sanu Sherpa became the first person to summit all 14 eight-thousanders twice, which he achieved from 2006 to 2022. Sanu Sherpa started with Cho Oyu in 2006, and completed the double by summiting Gasherbrum II in July 2022.

Reader's Guide

Cho Oyu is one of the 14 eight-thousanders. As measured by a variety of statistical techniques, the deadliest eight-thousander is Annapurna I, with one death (of a climber or climbing-support member) for every three summiteers, followed by K2 and Nanga Parbat (each with one death for every four to five summiteers), and then Dhaulagiri and Kangchenjunga (each with one death for every six to seven summiteers). Cho Oyu was the safest at 1.4% using the broad death rate metric from 1900 to Spring 2021. The mountain's first ascent was achieved during the summer season in the window between 1950 and 1964, a period when expedition-style climbing with large support teams was the only viable method. The first recorded attempt on an eight-thousander occurred when Albert F. Mummery, Geoffrey Hastings and J. Norman Collie tried to climb Nanga Parbat in 1895. The first successful ascent of an eight-thousander was by the French climbers Maurice Herzog and Louis Lachenal, who reached the summit of Annapurna on 3 June 1950. Due to its location in Tibet, Shishapangma was the last eight-thousander to be ascended for the first time; a Chinese team led by Xu Jing completed the ascent in 1964 (Tibet's mountains were closed by China to foreigners until 1978). The final eight-thousander to be climbed in winter was K2, whose summit was ascended by a 10-person Nepalese team on 16 January 2021.

Did You Know?

• Cho Oyu was the safest eight-thousander with a death rate of 1.4% using the broad death rate metric from 1900 to Spring 2021.
• Sanu Sherpa started his campaign to become the first person to summit all 14 eight-thousanders twice by climbing Cho Oyu in 2006.
• Polish climber Maciej Berbeka made the first winter ascent of Cho Oyu, one of three eight-thousanders he first ascended in winter.
• All 14 eight-thousanders were first summited in the summer season between 1950 and 1964, with Cho Oyu among them.
• Cho Oyu is one of the 14 mountains recognised by the International Mountaineering and Climbing Federation (UIAA) as eight-thousanders.

A Peak in the Death Zone

Cho Oyu holds its place among the fourteen mountains that the International Mountaineering and Climbing Federation officially recognises as eight-thousanders. To earn this distinction, a peak must rise above eight thousand metres above sea level and maintain enough topographic prominence to be considered independent of its neighbours. Yet the exact threshold for that independence has never been formally codified, and the UIAA has at various points debated whether the canonical list should grow to twenty peaks by admitting major satellite summits. What is unambiguous, however, is the geography: every one of these towering summits sits within the Himalayan or Karakoram ranges of Asia. More critically, each summit—including Cho Oyu's—lies deep inside what mountaineers call the death zone, an altitude band where the partial pressure of atmospheric oxygen is simply too low to keep a human body alive for any meaningful stretch of time. That single fact shapes every decision a climber makes on the mountain, from pacing to oxygen consumption to the narrow windows in which a summit push can be attempted and reversed.

Conquering the Winter Window

The winter ascent of an eight-thousander represents a tier of difficulty that summer expeditions do not approach, and Cho Oyu is no exception. Between 1980 and 2021, every one of the fourteen great peaks was finally climbed in the cold season, a span that began with a Polish team led by Andrzej Zawada putting Leszek Cichy and Krzysztof Wielicki atop Everest in February 1980 and ended with a ten-person Nepalese party reaching K2 in January 2021. Polish mountaineers dominated the early chapter of this winter era, completing nine of the first fourteen cold-season first ascents. Within that wave, Maciej Berbeka distinguished himself by making the first winter ascents of three separate eight-thousanders, including Cho Oyu, alongside Manaslu and Broad Peak. The fact that a single climber could claim three such firsts in the harshest season underscores just how much the winter window narrows the field of those capable of reaching a summit. For Cho Oyu specifically, Berbeka's achievement marked the moment the mountain was proven climbable even when conditions push well beyond what standard expedition logistics can support.

A Stepping Stone in the Grand Slam

Cho Oyu occupies a particular place in the history of the all-fourteen challenge because it was the very peak that Nepali guide Sanu Sherpa climbed first when he launched his extraordinary campaign in 2006. That opening ascent on Cho Oyu would eventually grow into the first-ever double completion of all fourteen eight-thousanders, a feat he finished in July 2022 by reaching the summit of Gasherbrum II. Beyond Sherpa's personal narrative, the mountain is an unavoidable waypoint in virtually every major fourteen-peak campaign. Reinhold Messner's oxygen-free tour in 1986, Jerzy Kukuczka's 1987 effort, Edurne Pasaban's 2010 women's milestone, Gerlinde Kaltenbrunner's 2011 oxygen-free women's first, Kim Chang-ho's 2013 speed record, the Meroi-Benet alpine-style couple's 2017 push, Nirmal Purja's 2019 six-month-and-six-day sprint, and Kristin Harila and Tenjen Lama Sherpa's 92-day record in 2023 all included Cho Oyu among the summits they had to tick off. In this sense, the mountain serves as both a proving ground and a benchmark, a peak that separates those who merely climb from those who complete the full circuit.

Context Among the Deadliest and the Distinguished

While Cho Oyu is not singled out in the statistical rankings of the deadliest eight-thousanders—a distinction that belongs to Annapurna I with roughly one fatality per three successful summits, followed by K2, Nanga Parbat, Dhaulagiri, and Kangchenjunga—its place among the fourteen still carries the inherent risks of the death zone. The mountain's first ascent, like those of all fourteen peaks, was achieved during the summer season in the window between 1950 and 1964, a period when expedition-style climbing with large support teams was the only viable method. The broader context matters: the first recorded attempt on any eight-thousander came as far back as 1895, when Albert Mummery and companions perished in an avalanche on Nanga Parbat, and the last first ascent was Shishapangma in 1964, held up by China's closure of Tibet to foreigners until 1978. Cho Oyu sits within this lineage of peaks that collectively define the upper limit of human endurance, each one a test of whether a person can function, make decisions, and turn back in an environment where the atmosphere itself works against survival.