The Caspian Sea is a unique ecosystem that has no outlet to the World Ocean, with the exception of the Volga River. The largest lake in terms of area on Earth, which has the characteristics of the sea: salinity, the bed of the Caspian Sea is composed of rocks of the oceanic type, and the tide regime is similar to that of the sea.The Caspian covers 371,000 square kilometres and is considered the largest inland lake due to its sheer proportions. It is huge owing to the inflow from several major rivers and reservoirs. It has an average elevation of 28 m below the mean sea level.
