Hi Gordon here I am as requeted.
I am an Avid Photographer who has used cameras from 35mm to 4"x5" View/Press Cameras including a Nikonos IVa underwater camera.
Have your fellow divers remove there regulators, allow the Air Bubbles to clear, watch out for silt and SMILE!!!.
Sometimes silt is unavoidable and it reflects light from the flash.
A grab shot, see how the bubbles are distracting.
My biggest tip is USE A FLASH, Water absorbs light and color. If your pictures are alittle BLAH, it is from the lack of light as even bright photo's can have a blue tinge to them.
I feel the Nikonos was the best Underwater camera ever made as I have used it as deep as 120' down (you just hade to go up to 90' or shallower to get the shutter button to come up) and there was very little drag while swimming with it.
But Digital has its advantages like the ability to review your pics almost instantly and not being limited to only the number of frames you have left on you roll of film.