GOKCHA, (Gök-Chai; Armenian Sevanga; ancient Haosravagha), the largest lake of Russian Transcaucasia, in the government of Erivan, in 40° 9′ to 40° 38′ N. and 45° 1′ to 45° 40′ E. Its altitude is 6345 ft., it is of triangular shape, and measures from north-west to south-east 45 m., its greatest width being 25 m., and its maximum depth 67 fathoms. Its area is 540 sq. m. It is surrounded by barren mountains of volcanic origin, 12,000 ft. high. Its outflow is the Zanga, a left bank tributary of the Aras (Araxes); it never freezes, and its level undergoes periodical oscillations. It contains four species of Salmonidae, and two of Cyprinidae, which are only met with in the drainage area of this lake. A lava island in the middle is crowned by an Armenian monastery.