Underwater photography is considered a challenging area of photography, it requires very specialized equipment and techniques to be successful. It offers the possibility of many exciting and rare photographic opportunities. Animals such as fish and marine mammals are the most common subjects, also shipwrecks, submerged cave systems, underwater "landscapes", and portraits of fellow divers.
The primary obstacle faced by underwater photographers is the extreme loss of color and contrast when submerged to any significant depth. The longer wavelengths of sunlight (such as red and yellow) are absorbed quickly by the surrounding water, so even to the naked eye everything appears blue-green in color. The loss of color not only increases vertically through the water column, but also horizontally, so subjects further away from the camera will also appear colorless and indistinct. This effect is true even in apparently clear water, such as that found around tropical coral reefs.
Here is a selection of some of my photography from a few of my favorite dive locations.
Links
Underwater Photography Course | Learn to Scuba Dive