Lake Baikal

It lies in Southern Siberia, between Irkutsk Oblast to the northwest, and Buryatia to the southeast, and it is also known as the Blue Eye of Siberia.
The Lake Baikal is the deepest and oldest lake in the world as well as the largest (by volume) freshwater lake, containing over 20% of the world's liquid fresh surface water and it is a World Heritage Site. Olkhon, the largest island in Lake Baikal, is the second largest lake-bound island in the world.