I agree with most all of the other posts here, but don't rule out a 3mm farmer John wetsuit and a dry top if that's all you can get. Board Surfers around the world use about a 5mm wetsuit for surfing in 40 degree ocean water in the winter time. A whitewater kayaker should be able to use a 3mm wetsuit with no danger of freezing to death since a kayaker will be in his/her boat most of the time (hopefully.) Just for insane fun, I combined a 3mm farmer john wetsuit and a drytop and swam about 200 yards across the lake to an island in the WINTER TIME. My girlfriend who was with me dressed the same. We did not freeze to death. We got a little cold when we first entered the water, but quickly warmed up and stayed warm. The water temp was around 45 degrees and the air temp was about 50 degrees. I agree that a drysuit would be the best choice, but don't ignore a wetsuit/drytop combo just because the younger generation doesn't think it's cool! As unlikely as it may be, a drysuit becomes worthless if you rip a big hole in it during a swim!