Lake Sevan is the largest body of water in Armenia and the Caucasus region. It is one of the largest freshwater high-altitude (alpine) lakes in Eurasia. The total surface area of its basin is about 5,000 km2 (1,900 sq mi). It is fed by 28 rivers and streams. Only 10% of the incoming water is drained by the Hrazdan River, while the remaining 90% evaporates. On the peninsula there is the monastery of Sevanavank, consisting of two rather rough churches. Initially the monastery was built at the southern shore of a small island. It is worthwhile to climb up the many stairs for the view and the green khachkars. They were carved from a plentiful local green stone and stand out from the others which are all made of tuff.