Reviewing The Beach: The History of Paradise on Earth, Adee Braun describes how “long before the beach was a theater of bodies stuffed into tiny suits, exposing as much skin as possible to the sun, beach-going was often a strictly medical undertaking”:

In modern Europe, only peasants sought refuge from the heat in the cool seawater. And so the beach remained mostly empty until the English looked around and began to consider the medicinal potential of their chilly national shoreline. Eighteenth century British high society suffered from a mess of maladies. Fevers, digestive complaints, melancholia, nervous tics, tremors, and even stupidity were the epidemics of the day. The pressures of urban life, pollution, and the general deterioration of society were obviously to blame. Enlightenment physicians began to consider new remedies for old ailments spurred by the new emphasis on science and experimentation.

Their new wonder drug was… water. Cold sea water, specifically.

Beginning in the late 16th century, English physicians endorsed the healing effects of cold water for everything from heat stroke to melancholy. It was believed that a brisk shock of cold water stimulated the entire body, promoting the circulation of humors and even contracting tumors. … By the mid-18th century a standard therapy was developed, which resembled waterboarding far more than a spa treatment. It involved dunking society ladies in the freezing sea repeatedly until the twin effects of cold and suffocation caused terror and panic (read: revitalization). The frightened patient would then be hoisted from the water in her soaking flannel smock, revived with vigorous back rubs and feet warmers, and deposited on dry land for a cup of tea. The adrenaline from the shock of cold was thought to have soothing effects on the body, calming anxiety and restoring the body-soul balance. The patient would repeat her regimen every morning for the next several weeks of her therapeutic seaside sojourn. The men got to take their therapy naked.

It wasn’t enough to nearly drown in the sea to relieve your stresses and ailments; you had to drink it too.