I think diving is a very eccentric activity, its eccentricity alleviated, I'll admit reluctantly, if you choose to dive in waters as clear and warm as those of the Florida Keys in summer. I qualified as a diver 20-odd years ago in the cold dark waters off Monastery Beach near Carmel, and though it was summer in California the green dark waters of the Pacific Ocean pressed in on me as though I was locked in a freezer. I floated down through the green pea soup and eighty feet down landed gently on an endless rippled beach which disappeared into the murk on all sides. Red rocks showed brown in color, green kelp looked black. I found diving sucked the life out of life itself. I quit after several attempts to enjoy getting cold in deep darkness.
Sailing in warm tropical waters I found a snorkel, mask and fins to be all the equipment I needed to enjoy bright sunlit colors and all the fish, corals and other sea life I needed to keep my little brain amused. Snorkeling the pristine waters of Central America was the cruisers way of "going to the movies." Some boaters liked to haul diving gear and air compressors around but I was content floating near the surface. It turns out humans throughout history have not been content and their curiosity gave rise to a long history of humans submerging themselves. Sufficient indeed to allow a migrant to the Florida keys to build his own History of Diving Museum. 
Its at Mile Marker 83 in the Upper Keys and its hard to miss, unless you are determined not to check out the north side of the Overseas Highway as you roll past Tavernier on your way south. I had never given it much thought but the history of diving is actually a history focused on diving helmets. You can't breathe, much less see, or work underwater unless you have a proper helmet. Halley, of comet fame pondered the problem and came up with this design, reproduced in the museum a few hundred years after the fact:
Personally I think this thing looks creepy and would probably have a heart attack were I to encounter it in a dark alley at night. The museum itself is fascinating, created inside an extended building with a self guided tour in a U-shape through various chambers that trace the evolution of diving (helmets).
The rooms are crowded with equipment, mannequins, displays and audio visual explanations and it is totally absorbing, even for someone like me who has little interest in suiting up and jumping in.
The museum has an absolutely staggering collection of helmets including one from each country that has ever produced a diving helmet and that alone, apparently is a claim to fame. They were all neatly aligned in a lighted audio-visual display. Next door there were literally piles of helmets of all shapes and sizes in abundance, all over the place:
That display looked pretty much alike to me, the fundamental commercial design is what it is, but the amateurish first efforts to create helmets ended up looking like a crazy quilt to my untutored eye:
From those early beginnings divers have learned to dress themselves in the underwater equivalents of armor plate which allows divers to work hundreds of feet down at surface pressures. This suit was made in Italy after World War Two:
The pride and joy of the display seemed to be the US Navy Mark V helmet, so unusual an item that they even displayed a fake copy of this Rolls-Royce of diving helmets, familiar to some of us from the movies. They showed four examples of the real thing on a rotating display:
And now I know more than I ever expected to know about the history of diving (helmets). It was $12 to get in and the museum has an easily googled website.
