The latest GoPro's have some really nice tech inside for getting video but not so great for photos imo. I may invest in something like an Olympus TG-6 if I go diving again and want some better photos. Nearly all cameras will need a diving housing if you go deeper down, even the GoPro. It's fine for snorkeling though.

The pros seem to use SLRs and dive housings but that's another level of cost/footage I know little about.