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Why do the Dead Sea and Great Salt Lake contain much more dissolved salt than typical seawater?

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Cluster of translucent, white salt crystals with sharp cubic shapes viewed under a microscope at high magnification against a dark background. — salt Salt crystal magnified.

The Dead Sea and Great Salt Lake contain significantly higher concentrations of dissolved salt than typical seawater primarily because they are located in arid environments where natural evaporation rates exceed the supply of fresh water from inflowing rivers.12

These bodies of water are situated in endorheic drainage basins, meaning they have no outlet for water to escape except through evaporation. Over time, rivers carry minerals and salts into these basins; while the water evaporates, the dissolved salts remain trapped and accumulate.312

In contrast, the open oceans are considered to be in a steady state, where the amount of salt entering the system is balanced by the amount lost, maintaining a relatively uniform salinity. Because the Dead Sea and Great Salt Lake lack this balance and are subject to intense evaporation in hot, dry climates, their salinity levels can reach values far exceeding the average ocean concentration of approximately 35 parts per thousand.231