Does anyone know anything about underwater bags for an SLR camera? I've seen some for smaller cameras, but nothing that would work for an SLR. I'm not looking to actually dive with it, but one of those "just in case" things. I plan to use it for boating and kayaking and such, and I just need something in case of a spill. If there's anything that's similar that I could use while snorkeling, that'd be awesome too. Thanks.