Triathlons have the swim leg first.
But what about someone who wants to relax and cool down in the water after a run? It is known that running (or any exercise really) raises body temperature a bit. It is (is it?) also known that sudden body temperature fluctuations are not a good thing.
So is there a real problem in jumping into the water while the body is still warm from the running - w.r.t body temperature regulation? How long of break is advisable before getting in the water after running?
Let us assume the water temperature is between a comfy 25-30 celsius. Although it would be appreciated if answers covered a broader range of water temperatures.