Already getting the questions: "How in the world does a surface photographer keep his camera dry?". While there are different brands and models that do different things, Francky preferred SPL Housings. They are not made to go very deep. The Aluminum Housings go to 15-20' and the SPL Plastic Splash housings will go to 40-45'. There are a number of customizations you can get, so the cost goes up with more features, but you will need to spend about $2000 for a Basic SPL set up. "Ports" or the individual housings for each lens type runs about $500 each.
Franck also mentioned that he got hit twice by windsurfers so hard that his housings cracked ruining his Canon 1D IV and 24-105 lens. Twice. Gulp. Needless to say, surface water photography is not only dangerous, it can be very expensive. I think I will start with a 7D set up first. lol
If you haven't already, you might want to swing by SPL's Website: SPL Water Housings