Closed lakes are bodies of water that do not drain into an ocean or river. This means that no water flows out of the lake. Instead, water is reduced within the lake via seepage into groundwater or evaporation. Closed lakes are also referred to as endorheic basins. The word endorheic originates from two words in Ancient Greek: ἔνδον, éndon, “within” and ῥεῖν, rheîn, “to flow”.
The largest lake in the world is also the largest closed lake in the world. This lake is the Caspian Sea with a surface area of 371,000 square kilometers (143,000 square miles).
Closed Lakes Tend to be More Saline
With a flow of particulate laden water entering the lake with no comparable outflow, closed lakes tend to be more salinic than open lakes. The amount of saline can vary greatly. The Caspian Sea contains 3 parts per thousand of saline while the Dead Sea, the deepest hypersaline lake in the world, contains as much as 400 parts per thousand.