The basic technique is to get close to the subject while balancing the lighting between foreground and background.
Underwater Photography Article Center
We went over to the Big Island for a week of “cillaxing” in February. Staying in a condo, we enjoyed several long drives around the island to visit the Volcano National Park, Hilo and the north end...
I managed to get out with Jack’s Diving Locker on one of their limited load trips one day. They did a great job with only 4 divers on a boat made for 8 or 10, for photographers it’s well worth the extra cost.