Cho Oyu is the sixth-highest mountain in the world at 8,188 metres (26,864 ft) above sea level.
Cho Oyu means “Turquoise Goddess” in Tibetan. The mountain is the westernmost major peak of the Khumbu sub-section of the Mahalangur Himalaya 20 km west of Mount Everest. The mountain stands on the China–Nepal border.
Just a few kilometres west of Cho Oyu is Nangpa La (5,716m/18,753 ft), a glaciated pass that serves as the main trading route between the Tibetans and the Khumbu’s Sherpas. This pass separates the Khumbu and Rolwaling Himalayas. Due to its proximity to this pass and the generally moderate slopes of the standard northwest ridge route, Cho Oyu is considered the easiest 8,000 metre peak to climb. It is a popular objective for professionally guided parties.
Cho Oyu’s height was originally measured at 26,750 feet (8,150 m) and at the time of the first ascent it was considered the seventh highest mountain on earth, after Dhaulagiri at 8,167 metres (26,795 ft) (Manaslu, now 8,156 metres (26,759 ft), was also estimated lower at 26,658 feet (8,125 m)). A 1984 estimate of 8,201 metres (26,906 ft) made it move up to sixth place. New measurements made in 1996 by the Government of Nepal Survey Department and the Finnish Meteorological Institute in preparation for the Nepal Topographic Maps put the height at 8,188 m, one remarkably similar to the 26,867 feet (8,189 m) used by Edmund Hillary in his 1955 book High Adventure.
Cho Oyu was first attempted in 1952 by an expedition organised and financed by the Joint Himalayan Committee of Great Britain as preparation for an attempt on Mount Everest the following year. The expedition was led by Eric Shipton and included Edmund Hillary, Tom Bourdillon and George Lowe. A foray by Hillary and Lowe was stopped due to technical difficulties and avalanche danger at an ice cliff above 6,650 m (21,820 ft) and a report of Chinese troops a short distance across the border influenced Shipton to retreat from the mountain rather than continue to attempt to summit.
The mountain was first climbed on October 19, 1954, via the north-west ridge by Herbert Tichy, Joseph Jöchler and Sherpa Pasang Dawa Lama of an Austrian expedition. Cho Oyu was the fifth 8000 metre peak to be climbed, after Annapurna in June 1950, Mount Everest in May 1953, Nanga Parbat in July 1953 and K2 in July 1954. Until the ascent of Mount Everest by Reinhold Messner and Peter Habeler in 1978, this was the highest peak climbed without supplemental oxygen.
Cho Oyu is considered the easiest eight-thousander, with the lowest death-summit ratio (1⁄25th of Annapurna’s). It is the second most climbed eight-thousander after Everest (whose height makes it the most popular), and has over four times the ascents of the third most popular eight-thousander, Gasherbrum II. It is marketed as a “trekking peak”, achievable for climbers with high fitness, but low mountaineering experience. It has a broadly flat summit plateau with no cairn (the traditional prayer flags on Cho Oyu’s summit plateau do not mark the “technical” summit), which can be a source of confusion, and debate, amongst climbers.