Big Almaty Lake is a natural alpine reservoir located in the Trans-Ili Alatau Mountains, 15 km south of Almaty in Kazakhstan. The lake is 1.6 km in length, up to 1 km in width, and between 30-40 m deep. The lake flows into the Big Almaty River and is part of the Ile-Alatau National Park. Depending on the time of the year, the color of the lake changes from light green to turquoise blue. The lake is the main water source for the residents of Almaty.