Old school, but bulletproof.
Hey, I've got a Nikon "Nikonos V" dive camera FOR SALE that I used to use for all my kayaking shots (I still put it in my raft gear on Grand trips as a solid backup). It's 35mm, but good to 250ft and tough as hell. Finally stopped wearing it on my chest/waist when it nearly beat me to death getting trashed in Jaws 1 hole on the Payette. It takes GREAT photos, if you're still in to 35mm stuff. Have 2 lenses: 28mm & 8mm, fixed. Email me if you're interested.
Otherwise, have gone digital like everyone else, and my money is on the Olympus 1030SW in the video above, plus a Canon Powershot A710 in a drybox, because it has a 6x optical zoom and image stabilization that really works. The Canon is faster and has better zoom, but not waterproof.
So many rivers, so little time..........