The Lake Issyk-Köl (Ysyk-Köl, Issyk-Kul) is the second largest alpine lake in the world after the Lake Titicaca in South America. The name, which means “hot lake”, is something of an exaggeration. A combination of great depth, thermal activity and mild salinity ensures that the lake never freezes, even in the harsh winters of Central Asia, despite being at an altitude of more than 1600 m.
The lake's origins are unknown, but the existence of a city built in the 5th century BC, submerged by flooding caused by an earthquake in the 16th century, has been demonstrated. Underwater expeditions over the years have found coins from that period.