In my early 20s, I took swift water rescue classes. They were fun, but kicked my arse. The first day, they made sure we were in the water and they worked us until we failed and needed help. Even with wetsuits, how quickly one became hypothermic and how quickly one looses strength stuck with me. That part of the training was deliberate and humbling. So many things stuck in my head, from how to ferry angle to how to tie certain knots unseen underwater, but two things repeatedly come to mind when ever I see a fast moving water. 1.) There is no fighting water. And 2.) eddy is your friend.
Edit to add: Anecdotes but germane,
