My Russian friends, Sergei and Natasha Every weekend they swim. When it gets cold, that is below about 5 degrees, Natasha dons a wetsuit. I don't think Sergei has one. I've seen them both swimming when it's blowing a gale at well below 0 degrees and when the tide is out this involeves a 500 metre run to the sea and back! They have been trying to convince me join them. They say it's healthy and all that, but it's hell of a price to pay for the rather dubious possibility of health benefits!