Are Oraca commonly found in water that won't cause hypothermia (eg death or unconsciousness) in less than an hour?

That would be warmer 50F==10C. Anecdotally, I have only seen or heard of people seeing Orca in the PNW and Arctic where swimming without a wet/dry suit is not only uncomfortable, but deadly.

Great White shark populations OTOH are concentrated in some of the most popular and temperate swimming areas in the world. Certainly, they are everywhere I have ever been swimming/diving.

http://voices.nationalgeographic.org/files/2013/02/1104_0729...