Lake Van the largest lake in Anatolia, lies in the far east of Turkey in the provinces of Van and Bitlis. It is a saline soda lake, receiving water from numerous small streams that descend from the surrounding mountains. Lake Van is one of the world’s largest endorheic lakes (having no outlet)—a volcanic eruption blocked the original outlet from the basin in prehistoric times. Although Lake Van has an altitude of 1,640 m (5,380 ft) in a region with harsh winters, its high salinity prevents most of it from freezing, and even the shallow northern section freezes only rarely.
Lake Van is 119 kilometres (74 mi) across at its widest point, averaging a depth of 171 metres (561 ft) with a maximum recorded depth of 451 metres (1,480 ft). The lake surface lies 1,640 metres (5,380 ft) above sea level and the shore length is 430 kilometres (270 mi). Lake Van has an area of 3,755 km2 (1,450 sq mi) and a volume of 607 cubic kilometres (146 cu mi).
The western portion of the lake is deepest, with a large basin deeper than 400 m (1,300 ft) lying northeast of Tatvan and south of Ahlat. The eastern arms of the lake are shallower. The Van-Ahtamar portion shelves gradually, with a maximum depth of about 250 m (820 ft) on its northwest side where it joins the rest of the lake. The Erciş arm is much shallower, mostly less than 50 m (160 ft), with a maximum depth of about 150 m (490 ft).
The lake water is strongly alkaline (pH 9.7–9.8) and rich in sodium carbonate and other salts, which are extracted by evaporation and used as detergents.
Lake Van is situated in the highest and largest regionof Turkey, which has a harsh continental climate. Average temperatures in July are between 22 and 25 °C, and in January between −3 °C to −12 °C. In particularly-cold winter nights the temperature reaches −30 °C. Lake Van mitigates the climate somewhat, so in the city of Van, on the shore of the lake, the average temperature in July is 22.5 °C, and in January −3.5 °C. The average annual rainfall in the basin of Lake Van, ranges from 400 to 700 mm.
The only fish known to live in the brackish water of Lake Van is Chalcalburnus tarichi or Pearl Mullet (Turkish: inci kefalı), a Cyprinid fish related to chuband dace, which is caught during the spring floods.In May and June, these fish migrate from the lake to less alkaline water, spawning either near the mouths of the rivers feeding the lake or in the rivers themselves. After spawning season it returns to the lake.
103 species of phytoplankton have been recorded in the lake including cyanobacteria, flagellates, diatoms, green algae, and brown algae. 36 species of zooplankton have also been recorded including Rotatoria, Cladocera, and Copepoda in the lake.
In 1991, researchers reported the discovery of 40 m (130 ft) tall microbialites in Lake Van. These are solid towers on the lake bed created by mats of coccoid cyanobacteria (Pleurocapsa group) that create aragonite in combination with calcite precipitating out of the lake water.
The Lake Van region is the home of the rare Van Catbreed of cat, noted for among other things its unusual fascination with water, and is surrounded by fruit and grain-growing agricultural areas.
According to legend, the lake is home to a mysterious sea creature, known as the Lake Van Monster which is believed by some to lurk below the surface of the lake, described as being 30–40 ft long with brown scaly skin and with an elongated reptilian head and flippers, resembling an extinct mosasaurus or basilosaurus. Apart from some amateur photographs and videos, there is no physical evidence to prove its existence.