Issyk-Kul or Ysyk-Köl (Kyrgyz: Ысык-Көл, IPA: [ɯsɯ́q kʰɵ́l]; lit. 'Warm Lake') is an endorheic saline lake in the western Tianshan Mountains in eastern Kyrgyzstan, just south of a dividing range separating Kyrgyzstan from Kazakhstan. It is the eighth-deepest lake in the world, the eleventh-largest lake in the world by volume (though not in surface area), the deepest lake whose deepest point is above sea level (939 meters or 3,080 feet), and the third-largest saline lake. Although it is located at a lofty elevation of 1,607 metres (5,272 ft) and subject to severe cold during winter, it rarely freezes over due to high salinity, hence its name, which in the Kyrgyz language means "warm lake".
The lake is a Ramsar site of globally significant biodiversity and forms part of the Issyk-Kul Biosphere Reserve.