The Canon ones are waterproof to like 100 feet, and I think they float too(good for that overboard camera situation). Pricy purchace. I think they are a few hundred bucks for sure. Lots of used ones out there. Check e-bay. B
I have the canon waterproof case for my canon camera, it is really, really nice, I want to think I spent something int he $140 range for it, spendy yes, but you can scuba dive with it.
Olympus(Stylus)makes a weatherproof one.I do not know if it is submersable.The Pentax Optio W10 is waterproof.One thing to look for is battery life.My Nikon Coolpix eats up batteries.I believe the newer models are better,mine never came with rechargable type.Only if you go with AA style,and those don’t last long.