In the 16th century Ambroise Paré prescribed sea baths for their astringent, warming, desiccating and many other properties.
“On Tuesday 3rd of June 1578, King Henry III and the Queens, after dining at Adjacet, went to sleep in Ecouen and in Dieppe where the king, following advice from his doctors, bathed in the sea to heal the scabies that tormenting him.”