: More on the accident ... What is cold shock?

I doubt the water could have been cold enough for cold shock. It is a lot more likely that exhaustion and hypothermia caused the drownings. Hypothermia can occur anytime the water or air temperatures are below 65 deg. Cold shock usually requires much lower temperatures. Cold shock can cause ventricle fibrillation and death in young healthy persons.

Don't underestimate exhaustion. Doing anything in water can be much more exhausting than doing similar activities on the hard. Last summer I set about scrubbing the bottom of my sailboat. I had on a shorty westsuit and work alongside the boat. This requires constant work to maintain position and gain leverage. After about forty minutes of this I suddenly realized I was feeling exhausted and nauseous. It took me about five minutes to regain enough strength to pull myself up on the dock and maybe fifteen before I felt better.

What hit me, is that because perhaps I was involved in getting the job done, I had no idea how much energy I was using and how far I was pushing myself. I either ignored or didn't get the usual warnings from my body. Perhaps there is something about thrashing about in water that allows us to push through those warnings. All I know, if I had been in cold water with nothing to cling to I would have been in real trouble. If our kayakers found themselves fighting to right and re-enter their craft they could have soon exhausted themselves to the point they were helpless.