Cho Oyu (or Cho Oyo or Mt. Zhuoaoyou) is the sixth highest mountain in the world. Cho Oyu lies in the Himalaya and is 20 km west of Mount Everest. Cho Oyu means "Turquoise Goddess" in Tibetan.

Cho Oyu was first climbed on October 19, 1954 via the northwest ridge by Herbert Tichy, Joseph Joechler and Sherpa Pasang Dawa Lama of an Austrian expedition. Cho Oyu was first attempted in 1952 by an expedition led by Eric Shipton, but technical difficulties at an ice cliff above 6,650m (21,820ft) proved beyond their abilities. Today, these ice cliffs are normally ascended using fixed ropes.

Just a few kilometers west of Cho Oyu is Nangpa La (5,716m/18,753ft), a glaciated pass that serves as the main trading route between the Tibetans and the Khumbu’s Sherpas. Due to its close proximity to this pass, climbers consider Cho Oyu the easiest 8,000m peak to climb. Cho Oyu was the fifth 8,000m peak to be climbed after Annapurna in June 1950, Mount Everest in May 1953, Nanga Parbat in July 1953 and K2 in July 1954.