Caspian Sea
The Caspian Sea, like the Black Sea, Namak Lake, and Lake Urmia, is a remnant of the ancient Paratethys Sea. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions, and is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.
Lake Baskunchak
The surface elevation of the lake is 21 m below sea level. It is fed by a river that draws from an area of 11,000 km². The salinity of the lake is about 300 g/l. Since the 8th century its salt was mined and traded along the Silk Road. Nowadays the lake's salt of distinct purity (99.8% NaCl) covers 80% of Russia's salt production. Depending on demand, 1.5 million to 5 million tons of salt are mined per year.