The one common thing I see in both video and still photography, that in-camera white balance setting for underwater are remarkably less important, and a powerful external strobe/lights, or better yet 2 make a WORLD of difference when subjects are within 5 feet.

If I were into still photography and bought a semi-entry level system, I would make sure that it had an upgrade path for adding external strobes, even the nice compact ones I see.

I have stepped all over the greenish images in Photoshop and all you can do is take a horrible photo and make it so it is amateurish. Marginal color photos, such as ones taken in real shallow water, or ones where you use internal force flash and you are within a foot of the subject come out ok, but nothing to honk your horn over.