Lake Sevan is located at an altitude of 1900 meters above sea level, the maximum depth is 80 meters. The lake is the largest source of fresh water in the Caucasus.
In the 1930s, it was decided to practically drain the lake. Fortunately, the solution was not implemented, but the water level was lowered by 17 meters.
To revive the lake, a tunnel with a length of 48 km was built through the mountains.