I reccomend the Pelican. It will protect your camera also... not just keep it dry. I lost a digital camera on a Westwater trip because it was in a dry bag that got tossed to shore at the takeout. Of course the impact didn't damage the camera, but it busted the can of bug spray... and THAT destroyed the camera.
Rule #1 never keep your bug spray with your camera.
Rule #2 keep your camera in something impact-resistant because your friends don't know there's a camera in your dry bag.
"Believe me, my young friend, (said the water rat somlemnly), there is nothing - absolutely nothing - half so much worth doing as simply messing about in boats. Simply messing...." -The Wind in the Willows