Canon A570IS or SeaLife Reefmaster dc600

[ethanb]

I've had very good luck with the A710IS, which is the "big brother" to the A570IS.  Before this I used a Canon S410.  I'm a huge fan of the canon compact cameras and their underwater housings - I've had extremely good experiences with both.  You're not going to get the quality of photos that you can with a housed SLR and wide-angle lens, but it's a unit you can carry with you on every dive and still enjoy the dive without the camera getting int he way.  With larger units, the dive ends up being "about the camera."  If you plan to use the strobe at all (i.e. anything but silhouettes or dives shallowed than 15 ft), you'll definitely want an external strobe, unless you're going to use it exclusively in 100+ ft viz. 

I wouldn't worry so much about raw mode - the sensors used in compact cameras don't really have the sensitivity to benefit as much as an SLR with a larger sensor.  There's a firmware hack (CHDK) that works on nearly all Canon A, S, and SD cameras that enables RAW mode, but I haven't seen huge benefits from it.  I really appreciate the real time histogram, overexpose marking, and improved battery meter it adds though.  I wish Canon would get onboard and support some of the features natively.

I'm not sure what differences there are between the A570 and A710, but I haven't seen anything bad in this series of cameras....

Ethan