Here is a scuba diving video I filmed with a GoPro Hero2 and of course edited with Kdenlive:
Underwater, colors fades to blue/green, so I tried to fixed them with some filters directly in Kdenlive. Details of the color correction process can be found here.

@drnn1076: Yes, everything was captured and rendered in Full HD. You'll find all these details on my blog post. As for the workflow, there's no special voodoo involved: just dump your footage in Kdenlive's timeline and edit ! :)
@DiveO: Yes, it's a GoPro HD Hero2. Here is the direct link to the color correction stack screenshot in full resolution.
And thanks DiveO for your warnings. I appreciate your concerns. This is something I find fantastic in the diving community: everyone is looking forward to make the activity safe and secure.
I'm aware of task overloading issues when underwater. And I found out that a GoPro mitigate these risks: with its big battery life and a huge SD-card, I just start it before the dive and forget it. The lack of LCD screen on that camera, if making framing nearly impossible, doesn't distract you from your environment and its dangers.
Of course, before bringing my camera, I asked the permission to my instructor. I only took the GoPro for my last pool dive, so he already knew about my behavior and calmness underwater. He would not have let me use my toy if he wasn't confident of my ability to manage it.
As for the location of my camera, the rationale was that having something on my head was a bad idea: it could prevent me from accessing and purging my mask. I can't risk (yet) to be blind.
I choose the arm for its accessibility: if something goes wrong or the GoPro get into my way, I can easily get rid of it. It's just a toy, less valuable than my life. I don't care if I have to buy a new one. I choose the left arm for the camera, to keep the right side free of distractions (this is vital to handling the regulators in case of emergency).