I'll leave the details to the others,
but just remember these points
1. you're going diving, not to plunder, leave the giant clams,
oysters, lobsters, fish ,crabs whatever alone ....
2. corals are dangerous, some can sting you, others are delicate,
you touch them they die, keep your hands to yourself, everyone's
happy ....
3. the sea is not a dustbin, watch where you toss your plastics and
rubbish ....
4. take only memories behind, no corals, no seashells, if everyone
takes a piece, then it becomes a big free-for-all
enjoy and have fun ! it's a wonderful sport ... 
