Historically, doctors would recommend their patients go to the seaside to improve various ills.
They would actually issue prescriptions detailing exactly how long, how often and under what conditions their patients were to be in the water.
Doctors use seawater for medical purposes even has a name: thalassotherapy.
In 1769, a popular British doctor Richard Russell published a dissertation arguing for using seawater in "diseases of the glands", in which he included scurvy, jaundice, leprosy and glandular consumption, which was the name for glandular fever at the time.
He advocated drinking seawater as well as swimming in it.
To this day, healing and spa resorts by the seaside abound..