Yes, I do some scuba underwater photography as well. It's true that a vast of my photography work is done while freediving, but I love strapping on the bottle and taking the deep dive once in a while.
I'm really into CFWA or "Close Focus Wide Angle" photography while scuba diving right now. What is Close Focus Wide Angle photgraphy you ask? Well it is pretty simple. It is the art of using wide angle lenses to get CLOSE to your subject. No, closer... A little closer... Yeah. That's about right.
Why would you want to do that you ask? Simple, you preserve the color, contrast, and detail of your subject underwater. Water eats light like crazy, and you lose reds incredibly fast. Not only that, but the farther you are away from the subject, the more detail and relief you lose. This technique lets you get right up close and drastically reduce the size ot the water column between you and your subject.
In the image above I only inches from the subject. My Tokina 10-17mm fisheye lens is practically in the chapon's face, and my two Sea & Sea YS-D1 strobes are pulled in tight to light up the subject. For this technique, you really need an ultra wide angle lens or ideally a fisheye or fisheye zoom. And you need to make sure the lens you choose focuses in close. The Tokina is ideal for this, as it focuses in practically right up to the dome.
Don't be shy, get out and get close to your subject for great color and image quality.
It was a pretty good first scuba dive of the year. We hit 40 meters, and even though the water was pretty cold, the chills didn't hit me until the very end of the dive. Plus, I was happy with the results. Not bad for being a little rusty and adjusting to the new camera.