In reply to Russell Lovett: I'm using a Drift Ghost HD with the 60m case. It's similar to the GoPro, but the built in screen, form factor and wifi functions swung it for me.
The dive case is great except for the inability to add a red filter easily.
Action cameras of this type do assume that you'll attach them to your person or kit in some way but that tends to give bad results underwater. I dive with mine hand held which gives two benefits.
1) It allows me to point the thing where the interesting stuff is easily without having to align myself to get the shot. This means you can track a fish or object easily as you pass over or by it.
2) It stops me waving my hands about to position myself in the water. This is a very good thing - watch a video of an experienced diver, they will clasp their hands in front of their chest or just cross their arms for the whole dive.
My son dives with a Canon Powershot SX220 or SX230 with the Canon case. It's bigger to deal with in the water but the video and single shots are very good. The ability to adjust the white balance gives much better results and failing that there is a third party firmware available that allows the camera to shot in RAW mode and hence gives you the ability to play with the white balance in photoshop or similar.
WARNING: Underwater photography can become very expensive.