Seriously? I have never heard, seen or experienced any such "snorkel requirement" on any dive boat or liveaboard in any of the numerous countries or islands I have dived. Moreover, I haven't worn (or carried) a snorkel since I was a wide-eyed newbie. Have you actually been approached with a snorkel prerequisite? If you are you just making sh!t up again like the "solo diver redundant equipment requirement", please stop doing that. You talked about diving in Florida and I can guarantee if a dive guide tried to enforce a snorkel requirement they would be laughed off the boat.