I have wondered that myself. The rivers they filmed on for the river wild are pretty intense, and the one in deliverance is even more difficult. I think it was probably not them some of the time. I have a hard enough time training my new guides every spring, let alone some Hollywood actors!
Yeah I know! Some shots are really realistic too!!! Same with Deliverance, one of my 10 most fav. movie... I usually just fast pass the pig scene though..hahaha..
Same with "Girl with the Dragon Tattoo" - loved the whole movie, but I'd have to fast forward the rape part if I'm gonna watch it again.
It's a shame really... they don't need those scenes IMO.