Achit Lake (Mongolian: Ачит Нуур) is the largest freshwater lake in the Uvs Aimag (province) of Mongolia, in the west of the country. At an elevation of 1,435 m above sea level it covers an area of 290 km². It is 28 km long, 16 km wide, and 10 m deep. The coast is covered with steppes, mostly hilly but swampy on the northwest and northeast. Several rivers also flow into the lake.