Can't supply you with anything but I can offer a few bits of information / advice on the Olympus option.
The TG-6 is certainly a good camera but if using it for serious underwater work I'd advise getting the custom housing for it. The TG-6 can be fitted with a supplementary wide angle lens, which is extremely useful for underwater use. Last time I bought one I think it cost £129. This is very cheap for a WAL, so don't expect especially good optical quality. Fine for underwater use - just avoid using the WAL for dry photography where there are a lot of straight edges, such as a forest of long straw stals, or you'll probably get some distortion. Also (and this is a slight pain) it's best to screw the WAL onto the TG-6 with both underwater, so the cavity between them is fully water-filled, otherwise trapped air may spoil images.
Don't try using the flash underwater or you'll likely get back scatter. Turn it off and use dive lamps and / or one of those cheap submersible flood video torches (available on Amazon) to light the scenes. You need as much light as possible.
Oh - and the maximum depth an unhoused TG-6 is rated to is either 12 m or 15 m (can't remember which on that model). But that's with seals in perfect condition. The seals are supposed to be replaced annually by an Olympus dealer but very few owners seem to bother. You might like to explore the cost / practicalities associated with this if buying a second hand camera. I killed a TG-1 a few years ago at only a few metres depth when it leaked slightly when overdue for seal changes. If you get the housing though you can forget about changing the camera seals, which might be more cost effective in the long run.
Good luck with your photography!