The underwater world needs to be captured up close unlike wildlife photography for example. Since the water refracts and distorts images, the closer you are to your photography subject, the less distortion you will have. A great deal of patience is required for under water photography. You may be trying to take a photo a fish or dolphin, but than they suddenly swim away before you get a chance to. Also, water contains many particles like plankton that can cause the image to lose contrast and sharpness.
Using an underwater flash, or strobe, will help provide the proper lighting necessary for taking a great picture. Therefore, it is essential to use an underwater camera with a flash. This will help to bring in other colors and contrast them with the colors of the subject. A medium sized strobe is all that is necessary as a large strobe can end up getting in the way.
Composition is extremely important. The same basic rules apply as in regular photography, but you should shoot at an upward angle towards the subject. Because of the camouflage technique of most sea life, they tend to blend into their habitats. Since they do not stand out like this, they do not make good photographs. The key is to always try to get a clear shot whenever the subject blends into the ocean background.
If you are looking to improve your under water photography skills, you will first need to work on your photography on land. When you get to the point where you are taking great photos on land, than you can move into the more advanced world of underwater photography, where taking great pictures takes more patience and skill. Photography under water brings sea life to the surface which gives us more information about the mysterious marine world. If you are just beginning to have an interest in under water photography you should consider taking an underwater photography course to learn proper technique.