Since Canon does not have an underwater camera that takes RAW, I have departed and bought (ouch) a Nikon underwater camera, the AW1 which does fill the need for RAW files and it has interchangeable lenses as well. However I would like to know what luck owners of the Nikon AW1 have had with keeping the camera dry. I had one that leaked and Nikon, thanks to them, replaced it in warranty. I have seen that some have had the same problem with the consensus being to use the 10mm lens instead of the zoom which is drawing suspicion as being the culprit in leak cases.
I have used the Canon D10 and D20 and gotten some nice images but only jpg. They are still nice images but not RAW. Here is one image taken with the Canon D20 that I was pleased with.