Thalassotherapy (from the Greek word thalassa, meaning "sea") is the use of seawater as a form of therapy.

[7] In Póvoa de Varzim, Portugal, an area believed to have high concentrations of iodine due to kelp forests, and subject to sea fog, the practice is in historical records since 1725 and was started by Benedictine monks; it expanded to farmers shortly after.

[citation needed] In the 19th century, heated saltwater public baths opened and became especially popular with higher classes.

[8] Others claim that the practice of thalassotherapy is older: "The origins of thermal baths and related treatments can be traced back to remote antiquity.

[9] The therapy is applied in various forms, as either showers of warmed seawater, application of marine mud or of algae paste, or the inhalation of sea fog.