Any shop can get nitrox. Lots of shops will pick up at Secrets. I use Living Underwater which has steel 120s for deep long dives with a small group. On one of them, the max depth was limited to 170', but I didn't get yelled out for going to 171' so I assume the rules aren't iron clad. That said, you may be limited on choice of dive site by whoever else may be on the boat and this maxim applies to all single-boat dive ops on the island. Some multi-boat ops try to match divers according to their skill level, but you still may not get to dive pretty much the way you want to dive unless you get your own DM and/or boat.