I’ve had Canon’s waterproof case for
our Elph for about a year, and have used it both on ww river trips and when on the beach (to keep salt spray off the camera lens). I have not had any problem with it at all. I do miss being able to use the camera’s viewfinder when it is in the waterproof case, but the LCD is bright enough for a sunlit day if I can shade it a bit with a hand.
I have noticed that the camera function button on the waterproof case is too easily nudged from Auto to the picture review position. I think I can rig up a blocking thingie for that problem. I have not had problems with fogging of the case, but silica dessicant packets would cure that.
Eric Nyre posted some wonderful illustrated instructions on how to make a foam cover to keep random drops off the waterproof case’s lens cover. The lens cover is big, so it’s possible to clean it quickly. In whitewater, I sometimes just tongue the lens cover, and then slosh it off in the river.