Sivash, also called the Rotten Sea, is a system of estuaries and gulfs of the of Azov Sea, bounded by Crimea on one side and Arabat Arrow on the other. Once Sivash was open from the sea and deep enough, but over time, the soft soil of the shores of the Azov Sea shifted, sediments appeared, new shoals and spits, and as a result it turned into what we see now. The coast of Lake Sivash is gently sloping, the water is stagnant, sometimes containing a large amount of hydrogen sulfide, which creates an unpleasant odor, and the depth is so shallow that sometimes you need to walk several hundred meters to go knee-deep into the water.
The Sivash is separated from the Azov Sea by a narrow strip of the Arabat Spit, which is more than a hundred kilometers long and tens of meters to half a kilometer wide. In the region Genichesk Sivash is connected to the Azov Sea by the Tonkiy and Promoina straits. Sivash itself is a complex combination of land and water - estuaries, straits, bays alternate with islands, peninsulas and capes. In total, Sivash covers an area of more than ten thousand square kilometers, a quarter of this area is occupied by water.
The territory of Sivash, located to the west of Lake Chongar, is called Western Sivash, this area is little studied, and its part, located east of Chongar, is called Eastern Sivash. Although the area of Sivash is very large, the depth rarely reaches three meters, and, basically, depths up to one meter prevail, therefore, in the summer, due to evaporation, the water area of Sivash is significantly reduced.
Winds pay considerable attention to the movement of water in Sivash - if an east wind blows, water from the Azov Sea through the Thin Strait near Genichesk enters the Eastern Sivash, and from there, through the Chongar Strait - to the Western Sivash, and in the case of a western wind, the movement of water occurs in the opposite direction. In addition to the water coming from the Azov Sea, Sivash is fed by ground and surface waters, and also precipitation falling over the lake.
The bottom of the Sivash is mainly a deposit of gray silt several meters thick. The content of minerals in the water of the Sivash is very different in different parts of the lake and directly depends on the flow of water through the Tonkiy and Promoina bays - for example, the salinity of the water in the Eastern Sivash varies from twenty percent in the northern part of the lake to almost ninety in the south, which is located farthest from the straits . The Western Sivash is distinguished by a significantly higher mineralization than the Eastern Sivash; its salinity is almost one hundred percent. Due to its high mineralization, Sivash was once used as a source of raw materials for the chemical and salt industries.