In terms of UW photographers, one of my favourites has yet to get a guernsey - Gary Bell. He seems to mainly work downunder, but has some superb topside and UW work that some other folks might enjoy. I wrote to him earlier in the year (looking for books featuring his work) and he mentioned that he is planning a dedicated coffee table book for some time later this year.
Anthony, if you don't already know, Gary's Great Barrier Reef coffee table book was published Steve Parish Publishing a few months ago.