I bought a waterproof camera case. I have a sony handycam, and it worked out cheaper to buy the sony waterproof case than to make one (and you get hand controls with it!)
Nick, use AE's time remapping, and make sure you have deinterlaced footage. Change the mode from frame blending to pixel motion. You should be able to slow it down quite a way (too much and the video will go strange - you'll know when it happens). You don't need to use super slow mo, but if you do, of course you can go even slower. I'm going to post a stacks video soon with my sister doing a front flip off a wakeskate. The shot goes for 10-15 seconds (from an original speed of half a second) If you have any difficulty, PM me and I'll send you some info.