Underwater Videocameras?

What are good Underwater Videocameras?
I planning a Film in that are need to used a Videocamera on a Canoe.
Any suggestions are welcome. I was think about sanyo or a Flip mino with underwatercase.
The Problem is that the sound is terrible under water.
Well i think the most scenes with dialog are over water but needs to be waterproof.
Well we have time to plan. And it depends on the budget what we get. but im exciting to film in water.
Its will be a new experience.