FLORIDA KEYS DIVING AND SNORKELING
The only living coral reef in the continental United States
Some come for the sun, some come for the fishing, and some come because it's the only set of tropical islands in the United States. The Florida Keys beckons all types of folks, but those who dive consider this a special mecca, a not-to-be-missed diving destination on the circuit. Primo reason: the reef.
The coral reef stretches all along the Florida Keys and parallel to them. In Key Largo, the reef is only about four miles from shore, and all the way out to Key West it's never more than seven miles from the land, and certainly always accessible by boat from any of the Keys. 
Beyond Key West, the reef makes its way to the Dry Tortugas, where it finally ends. It's really the main attraction of Key Largo, where the clear waters of the Gulf Stream make it one of the best snorkeling and dive spots in the world. Divers come here from all over the world and many of Key Largo's resorts cater specially to divers. The proximity of the reef is really what makes the Florida Keys special, and no matter how you choose to enjoy the reef, either by diving or snorkelling or just passing over it in a boat, you will feel grateful that you came to see this natural wonder.
Alligator Reef
Islamoradas most beautiful reef
At over 1/2 mile long, Alligator Reef is one of the largest reefs in the Keys. Spur and groove formations course down its descending slope, with numerous isolated coral heads as well. Divers will find all kinds of hard corals and soft corals, as well as a plethora of sponges. Grunts, parrotfish, grouper, and many schooling fish are common residents here.The USS Alligator is still visible a couple hundred yards SE (oceanside) of the lighthouse. The most commonly dived area lies about 600 yards south of the light tower.
Alligator Reef is one of the most popular divesites visited by Islamorada diveshops