I have personally spent a little over an hour in water only slightly above 0C and I was periodically diving under water during that time too. This was to free d

I have personally spent a little over an hour in water only slightly above 0C and I was periodically diving under water during that time too. This was to free debris from by boat’s propellor. I had a single layer on, kept calm and did not move more than necessary. I can assure you I am not dead :)