Does this help Peach?
Plus I wouldn't think that two minutes under the water would
cause hypothermia. But spending a lot of time in that cold mud would. It has to do with the Laws of Thermodynamics. There are a whole lot more cold molecules/compounds to suck the heat out of the racers in that mud pit, than in that 2 minute waterfall. Plus it is the needle in the haystack. The longer you look, the colder you get.
The above listings are in no particular order, except my memory.