Surface salinity corresponds to the equilibrium between evaporation, precipitation, the contribution of currents and rivers with different physical and chemical characteristics and to the oceanic mixing processes.

Most of the Patagonian Sea falls under the influence of sub-Antarctic waters, diluted by continental discharge, which originate in the southeastern Pacific and enter through the Magellan Strait and with the Malvinas Current.

In the northern zone, the discharge of continental waters from the Río de la Plata and the saline waters introduced with the Brazil Current, generate biologically important saline fronts.