I have a few sponsors (listed on my web pages) of my work. All of them are listed there for good reason -- they provide excellence in photographic gear and services.
I'd like to commend Reef Photo today, and the proprietor and fellow underwater photographer, Ryan Canon. Ryan Canon at Reef Photo is a star. He knows his stuff down to the last millimeter of detail. I am serious; ask him what port extension is needed to fit a 20-year-old Nikon 105mm AF Micro f2.8 lens, and he will tell you. I keep wondering when he is going to burn out since he seems to reply personally to all emails, with a level of detail that is astonishing.
Ryan's been a huge help to me and multitudes of other underwater photographers with his expertise and his retail operation. He's my first source now if I have a question about technique or what kind of gear might solve your problem, and I've been astonished at how much he remembers in terms of past questions. I think he knows what gear I have better than I do. He does take a few days to respond to my emails when he is busy, but I know that he always comes through in tight deadlines. Obviously, his patience is very high since he still answers my emails and questions!
If you are in the market for underwater photography gear, I can't give a higher recommendation than Reef Photo and Ryan Canon.