Lake Van is the largest lake in Turkey. It lies in the Eastern Anatolia Region 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.