Depends if you have not really used or don’t understand how to use and control a DSLR camera. I would suggest something more simple to get out in the water and still capturing nice images/videos. The new Go Pro Hero2 is an amazing little machine which captures nice images and at a rate of 10fps (frames per second) and the video quality is legit. Or just waterproof and shock proof camera from most stores.
Or if you understand how to use a DSLR camera and own one, I suggest getting a Housing for your camera
Websites:
http://www.splwaterhousings.com/
Go Pro:
http://gopro.com/products/?gclid=COuUsNHvxq0CFY-FpAodi1shiw
I hope this helps you, or anyone else with a similar question.