Fondueset, I am not a camera buff but I did look into compact digital cameras for a family member last year. I talked to several friends who have compact digital cameras & looked at numerous reviews.
Canon Powershots did very well in the general on-line pro & user reviews of digital cameras. (I have no Canon bias, in fact I always use Olympus for 35mm film). The
A75 seems good value (esp. if you shop around). Lots of features -- too many for my tastes
. There are higher res./spec. models (A80, A85, A90,A95,A610, A620 -I think they also have a flip-out-able LCD screen, which I didn't care for) the A75 seems more than enough for our needs though (the earlier A60 & A70 did v. well in reviews, you may be able to get upgraded A65 & A75s too?). You'd want to get some good rechargeable batteries to use with it. The pictures are excellent. We'll probably stick with this product range in the future (although I might take a look for a simpler sub-compact).
Have never used one in the water but I did see a good on-line
spearo movie that was shot on the earlier A70 model with waterproof housing (or bag?). Have never tried the movie feature - might be a nice addition to your gallery though?
Memory upgrades are pretty cheap & readily available now too (& getting cheaper all the time) [...somebody - a Sony owner - told me non-standard memory was an issue for the Sony cameras - is that right?].
[Don't know anything about Casio cameras but their Japanese watches were impressively robust (although I did accidently destroy one under...extreme impact conditions 
& a store owner broke the seal on another, but replaced & upgraded it -- interestingly the watch continued to work even with dirty Illinois lake water half filling it 
) ].