Uvs lake is the largest lake in Mongolia, which is 84 km in length and 78 km in width. The lake water is five times saltier than the ocean’s water and contains no fish, but it provides a habitat to over 200 species of birds. The lake is fed by Tes river and has no outlet. In 2003, the UNESCO listed the Uvs Lake Basin as a natural World Heritage Site. The site is made up of twelve protected areas representing the major biomes of eastern Eurasia. The steppe ecosystem supports a rich diversity of birds and the desert is home to a number of rare gerbil, jerboas and the marbled polecat. The mountains are an important refuge for the globally endangered snow leopard, mountain sheep (argali) and the Asiatic ibex.