Subjects must be approached cautiously with little or no disturbance to the reef. And, the photographer must locate an intimate angle to make the most dramatic photograph possible. The objective is to light, expose, and retreat- leaving only a memory of human contact. Exposing Film Underwater Factors unique to the underwater environment cause most land photography techniques to fail. Water is 800 times denser than air, with both organic and inorganic materials suspended in the photographic path.
Light absorption causes more color to be filtered out as depth increases.
Wave action and time of day influence the angle of light reflection, as well as the intensity of the light penetrating below the surface of the water. Light refraction also causes objects underwater to appear 33 percent closer than they really are. Therefore, objects must be measured in apparent rather than actual distance. To create aesthetically pleasing images underwater, you should start by identifying and isolating the main subject. Frames within frames, such as portholes or cave entrances, are good compositional elements to lend depth and perspective.