was not feeling well and here s one of his former coaches, speaking about how hot the water was, during the race. fran went under with about 1700 meters to go, they didn t realize it at the time, and, two hours later they found his body. if the water is too warm and salty, your dehydration level goes up so much faster. martha: dr. marc siegel joins us, a member of the medical a-team. that is exactly what you said to me. the saltwater combined with the high temperature of the water could have killed him? right. and we think of water as something which cools you and we have to remember water at this temperature, close to 90° and the swimmers said air temperature of 100° is enough to cause heat exhaustion and as you said, saltwater is high in salt. so instead of sweating out the salt, you absorb the salt and end up with your blood getting more and more salt and can fill your lungs with fluid. you could have a low potassium