Hi,

I have never shot underwater, but may be shooting some underwater footage for a film. IT would be in a river thats very clear. What type of camera and underwater housing do you guys recommend? I ve been using the Canon 5D and was thinking that for this shot perhaps a go pro with underwater housing would be a cheap way to go, allthough I don't know if thats best. The shots don't need to be moving around in the water too much.

You don'tgive us any info on what type of shooting you'll be doing. Is it just a static shot in water, just to give the viewer another angle, the GoPro probably will do fine... But is it critical shot of something special happening in the river I would not go with any other than a camera I can do some adjustment with.
Question about the best camera... The camera that you can work with to get the shot you need. Try to rent a housing for your 5D and se how it works out. If you are going to place the camera in the water and hope for a good shot (of a passing fish) than the 12 minute may be a limit.

Its for part of a short film. Basically to either follow or a static shot of 2 swimmers underwater in a clear river. Maybe renting the 5D housing would be the best option - I ve never done any underwater shooting that's why I am asking. I don't own a Go-Pro and I don't know if it would cut well with 5D footage either...

If you change camera between above and under water the change is less obvious. If the swimmers are just passning and if you can light the scene I thing no one would notist a change. You can probably rent a GoPro2 too. I think that you'll get the shot quicker with a GoPro with less job and an acceptible quality. But I you got the time to learn about the UW housing and do some testing etc etc than, maybe the quality will be better...

We use the GoPro all the time for water shots because it's cheap (err... inexpensive), and gets a good
colorful shot. If you are filming strictly underwater you need the flat port fix or it will be a little out of focus on the close shots. If you can get your hands on a housing for the 5d by renting that would be the best bet.
Check out this video we made and see the shots at 0.32 & 0.53 for a couple of examples of the GoPro with the flat port:

Main Resort Video for Wyndham - YouTube

As Bill has pointed out remember to get the flat port if you use a GoPro otherwise nothing will be in focus. If you have a 5D and want to use it you could also hire a splash bag. How deep will you be going, I would trust a bag deeper than a few feet. What lenses do you have for your 5D? you would want something pretty wide, like the 16-35. Also remember if using the 5D focus is different underwater you will need to be able to check critical focus especially with bigger sensor cameras.