My daughter who lives in the UK swims everyday of the year and shamed me into swimming on the shortest day of the year.
It was 12C or 53F both outside and in the water!
Yikes it was cold, as it was such a cold day I was going to run down in just a thong, just for fun as there wouldn’t be too many others about, but I chickened out and wore my new AussieBum “speedo” with a whale pattern. My wife went in first and then me, so we could photograph each other else no one would believe we went swimming in the depths of winter.
https://www.aussiebum.com/mens/swimwear Cockatoo whale briefs, check them out
Good fun, but I was seriously red from the cold, we didn’t stay long but at least we did it.