I'm not much of a scuba diver. My wife has her Dive Masters while I merely have an advanced certification. The idea of having to deal with neutral buoyancy and a camera at the same time doesn't sound like my cup of tea.
I do like to get wet though! And living in a part of the world that's hot all year round means I spend a lot of time in and around the water. My photography was always based around land activities but I got hired for a commercial job by a cruise company and they wanted some photos shot of snorkellers just under the surface of the water.
No scuba diving involved, just me being able to swim. So I bought a waterproof housing for my camera. It's made by Ewa-Marine, a German company, and I'm assured you can buy them all over the world. Ever since I've had the what-seems-to-be a giant plastic bag, I've used it to take all kinds of fun pictures under the water.
This one above was taken at a place called the Babinda Boulders and is my young niece Melissa when she was up here on holidays. I tend to put a wide-angle lens on the camera to show as much of the environment as possible and snap away. Shooting digitally means that you can take a lot more pictures than you ever could with film so you can experiment to your heart's content.
It's a relative snap to get the camera in and out of the bag and you can also attach a flash to the top of your SLR. There is a wide variety of housings for cameras available and the majority of them are precisely for this purpose. Shooting around the water and slightly under the water without having to be a diver. Again it all comes back to the finding a different angle on a subject. If you can get your camera to places other photographers can't you're guaranteed a new angle on an oft-photographed destination.