I'm presently shooting for a Scandanavian snow/skate/bmx company and I've had to do some water shots. I came up with the slightly stupid idea of building a waterproof housing for a 10x8" plate camera but after having been repeatedly smashed in the face from a 35mm camera and housing [which is about a sixth of the size] I'm starting to think twice.

Here is me accidentally firing the shutter as the lens port's smashing me in the nose -