You can also use the wide angle lens on the camera outside of the housing. Water filters light and removes some of the different colors. In the first 10 feet of water, virtually all of the colors in the spectrum pass thru the water. As you get below 10 feet, more and more of the red and yellow part of the light gets filtered out, but the blue light continues to pass thru to reflect off of objects-which makes them appear bluer than they really are. When you get below 80-100 feet, there's almost no red or yellow left, and even some of the blue is now getting filtered out.
Red objects appear very dark or even black, and most everything else looks blue or black.
A good color correction filter removes some of the blue light from the image, so that reds and yellows are relatively stronger. Above 10 feet the filter will make things appear too red. The same thing will happen if there is incandescent or halogen light illuminating your subject. Our filter is removeable while underwater to eliminate these problems. This is a very important feature.