Crypto (knots. Kryptos – “hidden” and lat. Depressio – “descent”) is a depression filled with water, whose surface is above sea level, and the bottom below sea level. Derived from the Greek word crypt, meaning hidden or secret, and say depression, which is an expression of the geography of the region is lower than the level of the sea surface. Cryptodepressions mainly lake. The biggest crypto depression in the world is Lake Baikal in Russia, and in Europe to Ladoga. On the Balkan Peninsula is the largest cryptodepression Skadar Lake.