How About a Cold Plunge?

I'm not quite there yet. Although, I do wonder how different it really is from jumping into our unheated pool? That got down to at least 59 degrees last fall before we finally closed it, and I was jumping into that. Obviously, a lake that still has ice on top is certainly colder, but I imagine there is a temperature that is just plain uncomfortable and it really couldn't get worse, right? Anyway, please talk to your doctor before conducting the experiment to find out.