Diving in the Florida Keys
A million divers and snorkelers find their way to the Keys each year. Some prefer the bait-and-tackle ambiance of the Middle Keys, and others are drawn to the touristy kitsch at the end of the road in Key West, while everyone has the reefs of the Upper Keys on his or her to dive lists. Since each island offers a unique combination of temperament, topside attractions, and diving, try each one until you find a Key that fits. All share clear, warm water, with visibility ranging from 30 to over 100 feet. In the summer and fall, water temperature is in the 80s, dropping to the 70s in the winter. The Florida Keys are America's islands in the stream with a homegrown great barrier reef — the third-largest reef system in the world after Australia and Belize.
Many of Florida's endangered and threatened species dwell in the Keys. And all the 100 species of hard and soft coral, more than 350 species of fish, and the countless invertebrates that depend on this ecosystem live on the edge, at constant risk from pollution, ship groundings, and other human-made and natural hazards. In recognition of the reef's biodiversity and its precarious nature, in 1960 Florida created one of the world's first underwater marine parks, the John Pennekamp Coral Reef State Park, off Key Largo. Thirty years later, with the designation of the 2,800-square-nautical-mile Florida Keys National Marine Sanctuary, protection has been extended to all the waters surrounding the Keys and the reefs beneath them.
Key Largo is Dive Central USA, with dive shops as common as casinos on the Vegas strip. Why all the action? The reefs here sit between a rock and a good place. The large limestone mass that makes up Key Largo prevents Florida Bay water — with a high nutrient level that would ordinarily limit underwater visibility and coral growth — from flowing out onto the reef. Offshore, the Gulf Stream, that near-mythical current, brings the warm, clear water that allows the massive reefs of the Upper Keys to thrive even though they're near the northern limit for reef-building corals.
As your dive boat leaves Key Largo, watch for the solid green of the mangrove forest that lines the coast. The Keys have very few natural beaches; instead, there are the mangroves, standing on stiltlike roots in a saltwater environment that would kill other trees. Vital to the Keys' environment, mangroves stabilize the shoreline and provide a nursery for the many species of marine life that spend their juvenile lives hidden in the tree roots.
Passing over the clear shallow water, you enter vast beds of turtle grass, important feeding areas for the reef fish. Soon you're over white sand dotted with isolated coral heads. Farther offshore, these heads are more numerous, forming patch reefs. At three miles, the first real reef line occurs. It's shallow — usually no more than 25 feet at its deepest — and made up of mound and branching corals attended by schools of smaller fish like grunts and snapper. Most dive boats cruise over the first reef, heading for the main reef about five miles offshore. Bright turquoise water inshore of the reef denotes the sandy bottom, while offshore the water is cobalt where the bottom drops into the abyss. In between lie the massive bank reefs of the Upper Keys, the superstar dives of America's reef system, with more than 188 separate sites marked by mooring buoys.