Chatyr-Kul (also Chatyr Köl, Chatyrkol, Kyrgyz: Чатыркөл) is an endorheic alpine lake in the Tian Shan mountains in At-Bashi District of Naryn Province, Kyrgyzstan; it lies in the lower part of Chatyr-Kul Depression near the Torugart Pass border crossing into China. The name of the lake means “Celestial Lake” in Kyrgyz. The lake and 2 km buffer zone around it is part of the Karatal-Japyryk State Nature Reserve. The lake is a Ramsar site of globally significant biodiversity (Ramsar Site RDB Code 2KG002).
The mean annual temperature in the lake basin is -5.6 °C (21.9 °F), with mean temperature of -22 °C (−8 °F) in January, and 7.1 °C (44.8 °F) in July. The maximum temperature in summer is 24 °C (75 °F), and the minimum one in winter is -50 °C (-58 °F). Some 88-90% of the lake basin's 208-269 mm of annual precipitation falls in summer. From October to end of April the lake surface freezes, the ice becoming as much as 0.25-1.5 m thick.
The water of Chatyr Kul Lake is yellowish-green with water transparency of up to 4 metres (13 ft). The mineralization of the lake ranges from 0.5 to 1.0 milligrams per liter (chloride, hydrocarbonate, sodium and magnesium type of mineralization). The salinity of the lake is 2 ppt. Mineral sources in the south part of the lake have mineralization of from 5 to 7 grams (0.18 to 0.25 oz) per liter and pH = 5,8-6,0. Flow rate is 1,866 m3 (65,900 cu ft) in winter and 3,629 cubic metres (128,200 cu ft) during summer.