I think the first thing before you go into photography is to learn how to be more of an effective diver. Effective in a way of maintaining neutral buoyancy, not touching the bottom, touching things, and breathing in a way where you will be restricted just by the bottom time and not the sac time. touching the bottom sure it is just sand but probably home to millions of creature and you're like a giant king kong that just step on a city underwater. So go out there and enjoy the marine life, besides, what you treasure should be in your head. You'll need it to get into photo when you got yourself pretty good. 
