What bodies of seawater tend to have the highest concentrations of salt?

The body of seawater that typically has the highest concentrations of salt is found in land-locked lakes, especially those that are endorheic basins, meaning they have no outlet. Over time, water in these lakes evaporates, leaving behind salts and minerals, which leads to increased salinity levels.

In contrast, while the open oceans do have significant salinity, they are subject to mixing with fresh water from rivers and precipitation, which can reduce overall salt concentration. Gulfs and bays are often influenced by freshwater inflow, which can further decrease salinity. Similarly, lagoons may also receive freshwater from rivers and rainfall, impacting their salt levels. Therefore, land-locked lakes, especially those that do not exchange water freely with other bodies, tend to have the highest salinity due to the evaporation process concentrating the salts.