Yes – running water can get down to minus 2°C. At least I found one Canadian physicist who instead of theorizing actually went out and measured it. Unfortunately I forgot my laser temperature measuring device today – but knowing what +2°C feels like it was very clear that today’s temperature was significantly lower because it hurt! Pain dies down quickly as the skin numbs and then you can immerse yourself more – but each new part in the water goes through a minute of hurt. Better adaptation of course removes the hurt but I’d not been in water for a week or so – only using cycling with minimal clothing as cold exposure instead for a while. Water definitely works best. I just don’t want to use the bath at home now because it’s treated with chlorine and is dramatically toxic. Eventually I’ll just have to though.