Karakul lake is the largest natural reservoir of Tajikistan that exist at the altitude of 3900m of sea level. It is 33km long and 23km wide. The big island – ridge, extended from north shore to the south, divides the lake into two parts: shallow – eastern and deep water – western. Its deepest point is in the western part which is 230 m. Up to the end of XIX century, the north part of the island was linked with shore through the narrow isthmus. Now this isthmus has disappeared. Few small rivers such as Qarajilga, Qaraart, and Muzkul fall into the lake but none of them flows out. There is no outflow from this lake and its water is salty.