Just be aware that if you go the DSLR path you will need big bucks and the camera and housing are bulky. DSLR is the route to professional photos but the learning curve can be steep. The cost of the camera is just a fraction of what you will need for a complete setup. My daughter went the DSLR route and ended up spending about $4K for the housing, strobes, arms, etc. A very good point and shoot with manual capabilities will cost you a fraction of what a DSLR system costs and will give you great pictures. I use the Sea&Sea DX-1G and my entire setup including two strobes, a wide angle lens, Arms, etc cost about $1800. I bought the strobes used off of ebay for a very nice price.
I also agree that buoyancy skills are critical to getting a good pics. Trying to adjust your camera settings, and get your object in focus while in a current or with no current can be a challenge.
Regards,
Bill