Lake Van is the largest lake in Turkey and Kurdistan. It lies in the far east of Turkey in the provinces of Van and Bitlis, in the Armenian highlands. It is a saline soda lake, receiving water from many small streams that descend from the surrounding mountains. It is one of the world's few endorheic lakes of size greater than 3,000 square kilometres (1,200 sq mi) and has 38% of the country's surface water. A volcanic eruption blocked its original outlet in prehistoric times. It is situated at 1,640 m (5,380 ft) above sea level. Despite the high altitude and winter averages below 0 °C (32 °F), high salinity usually prevents it from freezing; the shallow northern section can freeze, but rarely.

A soda lake or alkaline lake is a lake on the strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate, giving rise to their alkalinity. In addition, many soda lakes also contain high concentrations of sodium chloride and other dissolved salts, making them saline or hypersaline lakes as well. High pH and salinity often coincide, because of how soda lakes develop. The resulting hypersaline and highly alkalic soda lakes are considered some of the most extreme aquatic environments on Earth.