Hot and dry air causing high rates of evaporation but little precipitation, so the salt content of the water is maximized.
The normal maritime saltiness is around 35 sections every thousand (ppt) (3.5%), and almost all seawater has a saltiness in the scope of 31 to 38 ppt. Source doesn't make a difference. Likewise, saltiness has a tendency to change through the years as new water enters or leaves the seas. A few investigative studies have recommended that the North Atlantic and Pacific levels have differentiated.