Ay-Kul (; ; ), also called Oydinkul, is a small freshwater landslide dam in the Turkestan Range mountains in Kyrgyzstan, near the border with Tajikistan. The lake was formed after a massive landslide blocked the flow of the Ay-Kul Creek.
Ay-Kul is located approximately km south of Razzakov. It has a surface elevation of and covers an area of . There are no paved roads leading to Ay-Kul, and the lake lake is a popular destination for local hikers.
The Kyrgyz name for the lake is Ayköl (ÃÂùúéû), meaning "moon lake". In Uzbek, it is called Oydinkoûl, meaning "moonlit lake" or "clear lake".
Ay-Kul hosts an array of legends and myths among local Uzbeks. A popular legend holds that a shepherd lost his crook (variously described as having unique carvings or fitted with gold coins) in the lake, but months later found it in a spring in Dehmoy, Tajikistan.
Ay-Kul was formed after several cubic km of rock dislodged from the steeply sloped river valley of Ay-Kul Creek, a tributary of the Ak-Suu River. The lake freezes in late October and thaws in March.
Sources differ on the area of Ay-Kul, putting it from to . It has a maximum length of and a maximum breadth of .