The Keys—embedded in modern culture with their Margaritaville, hip/funky ambience—still offer a natural experience unparalleled in the U.S. It is the northernmost reef system in the country, the only one off the shores of this continent. The Keys stretch southwest in the outline of a crescent moon from the tip of South Florida, skirting the margins of the South Atlantic and the Gulf of Mexico. This 220-mile-long coral reef system parallels the splay of the roaded islands—even reaching to the more remote and westerly Marquesas and Dry Tortugas.

And it’s appealing to both novice divers and snorkelers, as well as the more experienced diver, with the linear bank-barrier reef growing from four to six miles off the windward shore in 20 to 90 feet of water. Patch reefs dot the entire system inside the leeward rim in only 10 to 15 feet of water, marked with great forests of staghorn and elkhorn corals.

This shallow reef has been snagging the hulls of ships for centuries, from Spanish galleons to more modern schooners and even sport boats. Marine archaeologists figure there may be up to 5,000 wrecks scattered around these islands—only a small portion of which have been found. They may be the distinguishing characteristic of these Keys.

In acknowledgment of this, NOAA—which manages the new Florida Keys National Marine Sanctuary—is setting up a "Shipwreck Trail" intended to help sport divers better locate and understand the maritime history of these wrecks. One is a Spanish colonial treasure galleon from the early 1700's; another is an American freighter fired on by a German sub in World War II; a third is a contemporary transport ship taken out of service in the 1980's. Along with six other historic and modern ships, this ghost "fleet" nurtures tropical fish, coral and even a bit of mystery.

Five ships on the Trail went to the bottom in storms or during battle, while the remaining four were intentionally sunk as artificial reefs. The "fleet" includes: the City of Washington, Benwood, Duane, Eagle, San Pedro, Adelaide Baker, Thunderbolt, Delta D, and Alexander's Wreck. The galleon San Pedro, near Islamorada Island,,is one of the examples made up of a collection of ballast stones and facsimile cannon, while others, like the steel-hulled Duane, look like a movie set of a shipwreck.

A series of charts with navigational coordinates, laminated underwater site maps, brochures, in situ plaques, and mooring buoys will help divers locate and better understand the historic nature of the wrecks. It’s a work in progress that will enhance the already rich diving in the area.

Some 43 of these islands are now connected by the "Overseas Highway." The embodiment of Jimmy Buffett's island village, it’s a tropical archipelago you can literally drive to from the mainland. Because of this and the scores of dive shops here, the Keys are the most popular and affordable scuba destination for U.S. divers. TIP: Avoid the larger "cattle boats" that carry 20 and 30 passengers, and opt for the smaller "six-pack" boats with a limit of only six—such as Quiescence in Key Largo.

You can jet to Miami or Orlando from any major city and then catch a short flight to Marathon or Key West. Or, you can drive. The best bargain is a dive package that includes room and full diving for the length of your stay—at about half of what you'd pay if you booked each individually. There is a wide range of rooms, from $45 to $300, up and down the Keys. For general info, can call 1-800-ASK-KEYS.

SUGGESTED READING:

Diving & Snorkeling Guide to the Florida Keys. By John & Judy Halas, Don Kincaid & the editors of Pisces Books.

The Florida Keys: A History & Guide [Updated]. By Joy Williams.

Reef Identification (Florida, Caribbean, Bahamas) guide series: individual guides: Fish; Creature; Coral. By Paul Humann. Edited by Ned DeLoach