Goycha is a lake in the Goycha mahal of the historical Iravan Khanate, later in the Novo-Bayazid uezd of the former Iravan governorate, and currently in the Gegharkunik province. It occupies the area of the former Kavar (Yeni Bayazid, Kamo), Yelenovka (Sevan), Garanlig (Martuni), Basarkechar (Vardenis) and Chambarak (Krasnoselsk) districts. It flows into Goycha (Sevan).

The name of the lake was noted as “Goycha darya”, “Goycha dangiz”, “Goychay”, “Goycha daniz” in Armenian sources. It was mentioned as “Goyja daniz” and “Gokja daniz” in the epos “The Book of Dede Korkut”.

The surface area of the lake is 1400 km², the average depth is 28.5 m, and the maximum depth is 83 m. The lake is located in the depression between the mountains at a height of 1900 m above sea level. It is the biggest and highest mountain lake of the Caucasus. It is surrounded by the Pambak mountains in the northwest, by the Basarkechar chain of mountains in the south, and the Shahdagh in the west. 28 rivers flow into the lake and only one river, the Zangi (Hrazdan) River, flows from it.

The lake was named Goyja or Goycha for the colour of water (for being clean and fresh).

In the early 20th century Goycha was renamed “Sevan” (Sewank) by Armenians for the Alban monastery built from the black stone on its shore.