Lake Teletskoye (Altay: Altyn-Köl) is the largest lake in the Altai mountain system and the Altai Republic, Russia.
Situated at a height of 434 m above sea level, the lake is 78 km long and 5 km wide and lies between the mountain ridges Korbu and Al-tyntu . Its surface area is 233 km²; however, due to its considerable depth (325 m), the lake contains no less than 40 km³ of fresh water.
About 70 rivers and 150 temporary streams flow into the lake, the largest of them, Tchulyshman River , supplying more than half of the lake's water. The lake is drained through a single outlet, the Biya River, which, after its confluence with Katun River, forms one of Siberia's largest rivers, the Ob River.
