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1. Get used to shooting upside down.
   The camera doesn't care if you're standing on your head, and you get used to it quickly. This helps you shoot horizontally, and very typically you will be shooting under rocks and crevices where the fish hide. If you try to get down and shoot in normal orientation, you will take more time to get there, have trouble staying there, and often just not fit. Popping your head and camera down from above is no problem, though. You get there faster and easier, have more time to shoot, can hold your position easily by gentle finning, and will be in a lower, more favorable camera position.

   Consider wearing a weight belt.

   Even if you don't normally use one. It will make it much easier to get down and hold a low and motionless position while waiting for fish get with your program. (And they're even dumber and less co-operative than human models)

   Preview your shots.

   Scout the shot before shooting, setting things up. Don't just open fire. Circling around to find good angles and composition is obvious in land shooting, but people tend to get "buck fever" and rush their shots when underwater. It's worth taking a half dozen dives before snapping that one great shot.

   Respect the rules of composition.

   Again, just because you're underwater doesn't mean the rules of esthetics have changed. If you want pretty shots, not just a trophy collection, remember background, framing, shapes, and inclusion, all that. You still have to watch out for backlighting: if you want to shoot against the East coast of an island, you'll do better in the morning, and so on. Generally, framing shots attractively is easier in the complex, pretty underwater environment. It only takes a second to make sure you aren't cutting off part of the subject, or that the subject is entering, not exiting the frame. If you're not aware of using circular and triangular composition, or the Law of Thirds, check them out: your pictures will improve.

   Study the fish.

   The more you learn about the way they act, the better your pictures will be. Fortunately, it is much easier to study fish behavior, especially in shallows and in reefs, than wildlife on shore. If you approach angelfish from various angles, you will learn when they will just take off and when they will turn sideways to see what you are up to. And how close you can get before they do. Use this knowledge to get profile shots.

   If you freeze (or go away then return) fish will usually come back.

   Again, a little study will teach you this. Damselfish will disappear, but never go far from the coral they are hanging out around. Eagle rays or sea turtles will just get the hell out of Dodge and that's that. You will almost always see more fish if you stop moving. Moving, you look like a big predator. Motionless, you look like a floating log--some fish will even school up on you.

   Don't shoot down, shoot across (or even upwards).

   One major thing that separates amateur dive shots from the great ones is the tendancy to shoot downward, instead of getting down there and shooting parallel to the bottom. You see some beautiful sponges or corals with wrasse hovering above them, great. If you shoot straight down you'll get an un-natural shot of fish spines against a cluttered background. Going down (remember, head-first is easiest) and taking it horizontal will yield a natural look, fish seen in profile, and even a blue water or surface background if you do it right. A bottom background will usually be busy and dull. Shots of the surface are almost always pretty, by the way, with an ethereal quality. But you have to watch out for backlighting and silhouetting if you can't fill the subject with flash.

   Make those fish pose.

   You can do more of this than you might think. If the fish flit when you dive down into their cave, why not try lying above, out of sight, and just sticking the camera down and firing blind? Worth a try. When you know they're there, ambush them. And don't forget that a little bait does wonders. Even a sting ray looks pretty mundane from directly above. And the thing about skates, they will often freeze when you approach, hoping they are not seen. If you come in very low, right into his face, and are ready to fire when he moves, you might get something pretty cool.

   If you are out with a buddy, try driving fish towards each other so you can shoot them head-on or sheering off. Most larger fish can be driven very easily and if your buddy is lurking motionless, maybe hugging a rock, they might get pretty close to him before they sheer off, presenting their profiles. On the other hand, chasing fish very seldom yields good shots, unless they are going into a cul-de-sac (and it's pretty hard to chase a fish into a place he can't wiggle out of).

   If you have the option of focusing, remember to focus on the subject itself. In close, focus on the eye of whatever or whoever. If something big is coming towards you with open mouth, try to focus on the edge of a tooth.

   Learn to shoot without viewfinder.

   Not only is it hard to see in the viewfinder window, your mask moves it away from your eyes--so you end up seeing a narrower field of view than the camera will actually shoot. Furthermore, it is often very difficult to get your whole head into the proper position to view and shoot. It's a good idea to pay attention what shots you get when holding your camera at various distances from the subject so you can "shoot blind" when you need to. Hey, news photogs do this all the time, lifting their motor-driven Nikons over their heads in crowds. And face it, your camera will probably not allow much close-up work or a lot of precision: the plus side is that the wide-angle lenses don't require much focusing. As you learn what you will get from various distances, you will find it easier to use the camera away from your eyes and become more versatile.

   Be Creative!

   A surreptitious trip to the aquarium can round out that assignment nicely, I've found. And don't forget the life-like plastic fish you can get at the Nature Store and pose however you want. But personally, I find the best technique is taxidermy. Catch the fish using your spearfishing wiles, angling skills, or poison and dynamite, then have them attractively stuffed, anchor them in a fetching pose, and shoot away. I've proposed this with human models, especially children, but it's never really caught on.