Down here in Floriduh one of the big "boater killers" is when people get real hot, they jump out of their boats and go swimming for a bit. Then they try to climb back aboard and realize they forgot to put down a decent ladder to get back aboard. Without traction or ladders, they can only play 'buoy' for a while before becoming exhausted. This of course is more common whjen the boaters are drunk and forget these things...
But in Washington, the temperature of the water should prevent even a bunch of drinkers from getting an urge to go swimming.