In my hometown, in Ireland, there were people who would swim in the sea every day of the year (unless stormy). This is common across many Irish coastal towns. T

In my hometown, in Ireland, there were people who would swim in the sea every day of the year (unless stormy). This is common across many Irish coastal towns. The old people in my town who were regulars, including men in their 80s, would claim it is very healthy and that they rarely become ill. I now live too far from the sea to do it regularly but I was just up in Cape Cod at the weekend and took a dip in the ~40F water. This was on the colder end of what I would ever do back home and I wasn't accustomed to it, so it was a little difficult but I certainly felt very refreshed after! I still usually do, as others have commented, turn most of my morning showers to cold at the end, if not taking them entirely cold, but it's just not the same... The saltiness of seawater in particular seems to be very therapeutic and might be an additional factor.