Gokyo Lakes are oligotrophic lakes in Nepal's Sagarmatha National Park, located at an altitude of 4,700–5,000 m (15,400–16,000 ft) above sea level. These lakes are the world’s highest freshwater lake system comprising six main lakes, of which Thonak Lake is the largest. In September 2007, Gokyo and associated wetlands of 7,770 ha (30.0 sq mi) have been designated a Ramsar site.
The Gokyo lake system of 19 lakes is spread over an area of 196.2 ha (485 acres) lying between 4,600 and 5,100 m (15,100 and 16,700 ft). The wetland lies on the head of the Dudh Kosi, which descends from Cho Oyu.