Of all the different types of photography showcased on Smashing Magazine, underwater photography is probably one of the most difficult to practice. It requires a very specialized equipment and the knowledge of some advanced techniques to get a perfect picture. You need to get the correct exposure, accurate focus, controlled movement of your subject and a pleasing color balance; you also have to deal with low light. Underwater photos offen suffer from loss of color and contrast when taken at a significant depth. Such photos are always adjusted with color balance to help offset the blueish tint of the water.
Because underwater photography is a specialized art, relatively few photographers attempt it. But it offers many exciting and rare photographic opportunities for fresh and truly different vivid images. Most often, photographers use a traditional film or digital camera covered in a watertight casing. Professionals prefer to use special underwater cameras.
Victor Amor
J.Lambusphoto
Scott (lundysd)
Numera Tokyo
National Geographics
Kenvin Pinardy
Sugarock99
Dustin Humphrey
source: http://www.smashingmagazine.com/2008/10/19/25-beautiful-examples-of-underwater-photography/