Lake Bliznaka is the largest in area of the Seven Rila Lakes.

It is located 1,940 meters north of Vazov Peak and is 2,243 meters above sea level. The catchment area is 2.10 sq. km. The water surface area is 168.6 acres. The water volume of the lake is 590 thousand m3, and the maximum depth is 27.5 meters. In terms of depth, it is in third place after the Eye and the Kidney.

In the recent past, the lake was called Cifte göl. The name "Twin" comes from the fact that during drought the lake splits into two small ponds. From this it acquires the shape of an hourglass.