Gokyo Lakes are oligotrophic lakes in Nepal's Sagarmatha National Park, located at an altitude of 4,700–5,000 m (15,400–16,400 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.