Shucks, I thought I would be the 1st one to mention snake boots but GSP beat me too it!!!!
I picked up a set at "Sports Authority" in Anchorage when I was in town last year.  They had them on closeout.  Started at around $100 I think & they were down to $19!  I guess they forgot there are no snakes in Alaska when they ordered them. BUT, being 15", Gortex, & only $19 (Lacrosse brand) I figured I'd give them a try on an upcoming trip.
Have to say I was impressed.  When these wear out I'll get another set, even at full price.  Very light & ankle support is great on rough portages.

GSP, I'd like to hear the storry on your "swim".