Sorry I'm so late in posting this. A popular activity along the Lake Michigan shoreline (and, no doubt the shores of other lakes in cold areas of the northern hemisphere) is the "Polar Plunge", "Polar Bear Plunge" and the like, on New Years' Day. These guys below, in the thermal wet suits......are waiting for these guys/gals, in the birthday suits (with a few accessories).
I was there to watch, and it was COLD just standing outside in the cold with a strong breeze off the Lake. maybe some year I will try this, but this was not that year!