Polynesia is a wonderful paradise for divers and underwater photographers! I suggest you to go to Bora Bora and enjoy dives with lemon sharks and blacktips sharks...
You can also see a lot of kind of sea-life animals (nudibranchs, trevally, shrimps, rays...) in different level dives, from easy to very hard ones!
Always take with you the digital camera, with a power strobe if you can!
You'll have a lot of opportunities to have good shots in the deep water of polynesian ocean!