As the saying goes "not if, but when". I've never had a problem as long as I've been carrying a camera (which is about every dive since '98). Buttt !! On my first dive, aboard the Vision on a 3 day Channel Island trip, as soon as I got to the bottom and tried to take a shot of a cooperative Garibaldi, I saw a strange blinking ERR message in the finder. I'd double /triple checked that every thing was "good to go" as usual so I couldn't imagine what the problem could be until I saw the huge puddle forming in my housing !!! I knew that the damage was done so I slowly made my way to the surface, took my waterlogged Fuji S2 out of the housing, said a few choice phrase's, grabbed my gear, and jumped back into the water. After all, it's the dive experience that counts most.
Fortunately, Ken Ashman, of CaliforniaDigitalDivers was aboard, and seeing my plight, offered to loan me which ever of his 2 cam's/housings he wasn't using at the the time. Talk about trial under fire (or is that underwater) !! I grabbed his D100 in a Tetra housing w/who knows what strobes and jumped back into the water. New camera, new housing, new manual strobes, who cares !!! I had a camera in my hands and the basics apply to any camera. It only took about 5 shots to figure out what was what and then I was back in my element. But then I'd trade off to a D70 in an Aquatica w/ totally different strobes and have to learn everything over again !! It's a vacation, I was there dive, and I had a lot of new "toys" to play with, but at least I was getting a few shots. Another diver/photographer that I'd met last year, Richard ..., offered to call to Samy's Camera in Santa Barbara as soon as he got cell reception on our way back and managed to find another S2 (used/body only $450) that was waiting for me if I could make it to the store 1/2 hr after we docked !! I did, and the followup 4 day landbased trip to Catalina was salvaged. But, there were a few hesitant moments, the first time I took my own rig rig back U/W, but as usual, I never had another problem.
What caused the initial flood ? I ever so slowly dissected the housing looking for a clue, a hair, a nick in an O ring, anything !! But everything looked perfect. Who know's! It really is "Not if, but when" !!