If you've got some more pennies to spend and fancy a DSLR, take a look at the Olympus E410, 14-54mm lens and the water proof housing to suit. Great compact DSLR (smallest on the market) and would be ready to dive.
All depends what level of photography you want to do. Holiday snaps or just quick fun snaps then any "waterproof" compact will do. If you want quick auto focus, more frames per second, better low noise at high ISO etc...then go down the DSLR route. You wont regret it
The waterproof housing in the photo is for thw olypus 7-14mm wide angle.