Syvash

Syvash or Sivash also known as the Rotten Sea ( _uk. Сиваш, Гниле Море; _ru. Сиваш, Гнилое Море; _cr. Sıvaş, Çürük Deñiz), is a large system of shallow bays on the west coast of the Sea of Azov (northeastern coast of the Crimean Peninsula, Ukraine). The total water area: 2 560 km², length: 200 km, width: up to 35 km. The total water/land area of the Sivash system is over 10 000 km². It separates the Crimean Peninsula from the mainland, and a part of the border between the Autonomous Republic of Crimea and the Kherson Oblast of Ukraine passes through Sivash. It is separated from the sea by the narrow (max. 500 m) and long (110 km) Arabat Spit and is connected with the sea through the Genichesk Strait by the port town of Genichesk. The Isthmus of Perekop separates Sivash from the Black Sea.

Sivash is extremely shallow. The deepest place is about 3 m, with 0.5-1 m being the predominant depth. The bottom is covered with silt up to 5 m thick. Being very shallow, the waters in Sivash heat up in the summer and produce a rotten smell, hence the name, "Rotten Sea". For the same reason the water is extremely salty. The amount of various salts is estimated at 200 million tonnes. Several plants harvest the mineral resources of Sivash. The Sivash area is a wetland of international importance. The shores are low, slightly sloping, swampy and salty. In summer the water level of Sivash decreases significantly, revealing fruitless solonets soils called "sivashes" by locals.

Sivash is naturally separated by the Chongar Strait into Western Sivashes (Western Sivash) and Eastern Sivashes (Eastern Sivash), the latter being separated from Crimea by the Genichesk Strait.

In the history of the Russian Civil War, Sivash is known for its surprise crossing by the Red Army during the Perekop-Chongar Operation.