Let me cast a vote for the Pentax Optio W30.
I bought one (actually its predecessor, the W20) for my daughter to use snorkeling, on our boat, around the pool, basically any wet environment. It has been a champ.
We've taken it snorkeling at St. Thomas last year, Cabo over thanksgiving, and two weeks ago in Cozumel. And it was great climbing the falls at Dunns River. The under water video is some of the funniest we have from our trips.
the unexpected surprise, is just how good it performs on dry land. My Canon died on our most recent trip, and it was great to have this camera as a "back up'. It was a lifesaver to have a second camera along.
There are a couploe of tricks to remember with either the Olympus or the Pentax. They are only waterproof down to limited level; they are for snorkeling, not diving. And they are only rated for a limited time in the water, generally 30 minutes. The other thing is remember to rinse them with fresh water after being submersed in salt water; we usually use somee of the bottled water we're carrying.
Check out www.dpreview.com
for more information about digital cameras than you'll ever need.