Sounds like a fab holiday and the dogs will love it.
Just a word of caution tho, please keep them away from the white water!!
We went to watch some rafting in Wales many, many years ago, our very well behaved gsd was off lead with us, he slipped on a rock and fell in to the fast flowing water and was swept quickly downstream, if it wasnt for the the damn fast reactions of a family friend who jumped in knee deep and practially hauled him out by his fur, we dread to think what would have happened to him!! The friend is not a keen doggy person but just reacted!

They may be strong swimmers but woudlnt stand a chance against the rocks or if they got caught in a stopper.

Sounds like you will have an amazing time, and what lucky dogs.