It seems that with the advent of point and shoot digital cameras and cheap underwater housings, just about everyone has a camera to go diving with. This phenomenon has many pluses and minuses, but I must say that the minuses thus far, at least in my experience, seem to outweigh the pluses.
Without trying to be an elitist snob diving takes practice and skill. In order to achieve proper buoyancy, one must be comfortable in the water, and must know where all body parts and all extensions like fins are at all times in relation to the world around you. Most of the places we dive today are protected (thank goodness), meaning you are not allowed to touch the reef or the creatures living there. A careless fin, laying across coral for a photo, standing on coral, etc. can cause significant damage that takes a great deal of time to repair. I must say that I'm very lucky to have been originally introduced to ocean diving by people who took their responsibility to the environment very seriously, and taught me not to ever touch live coral or other creatures.
In order to shoot photos with most cameras (especially point and shoot digitals), you must get close to your subject. As you get close to your subject while diving, you generally must get close to the reef. As you get close to the reef, lack of buoyancy control will cause you to trash everything around you as you madly flail in order to get that picture that your family and friends just MUST have.
The more excited a photographer gets about the subject being photographed, the more he or she forgets that there are living creatures around (including fellow photographers). This week, I have watched a person lay on the reef and become incensed when the divemaster picked him off the coral and told him not to do this. I watched an excited photographer kick another photographer in the head as he cut her off for a picture of a file fish. I've seen numerous people kick over gorgonias, sponges, and soft corals while trampling each other for a photograph of a seahorse. I was personally shoved to the side by someone who wanted a picture of a frogfish I was filming (I have video of his camera cutting in front of mine), and the ruckus caused the frogfish to just give up and leave, moving to another spot. Unfortunately, that didn't stop the paparazzi, who chased him to the new spot and started all over again.
So, as a dive instructor and an underwater photographer and videographer, I have some suggestions. 1) Do not put a camera in your hands until you can demonstrate proper buoyancy AND dive without using your hands. 2) If the subject you wish to photograph is in a poor spot for you to get close enough without banging into something, come back later. It might have moved. 3) Take turns. Just like in kindergarten. Chances are, the subject won't be going far. It is not a feeding frenzy, and you'll likely stress the animal and yourself before you get a decent picture. 4) Make sure you are weighted properly for all aspects of the dive. Late in the dive with a light tank is not the time you should find out you can't hold position to shoot that squid who is coming right at you. 5) If you see ME shooting...do not taught happy fun recalcitrant videographer. I will bite, or inflate your BCD and send you to the surface.
I did laugh pretty hysterically today when the paparazzi chased a turtle around the reef. As they all clamored for position, the turtle took off and hung out with me for a good 4 minutes of video. He got so close that I had to pull back so he'd be in focus. Same thing happened with a frogfish. He wound up directly in front of me where I got some great video. Ditto with a seahorse.
To see video shot without crashing onto reefs, go to this handy link