Your Keys experience begins on your 18-mile drive south on "The Stretch," a portion of U.S. 1 with a specially colored blue median that takes you from Florida City to Key Largo. The real magic starts at Mile Marker 113, where the Florida Keys Scenic Highway begins. As the only All-American Road in Florida, it is a destination unto itself, one that crosses 42 bridges over water, including the Seven Mile Bridge—with its stunning vistas—and ends in Key West. Look for crocodiles, alligators, and bald eagles along the way.

Key West has a Mardi Gras mood with Fantasy Festival, a Hemingway look-alike contest, and the occasional threat to secede from the Union. It's an island whose eclectic natives, known as "Conchs," mingle well with visitors (of the spring-break variety as well as those seeking to escape reality for a while) on this scenic, sometimes raucous 4x2-mile island paradise.

Although life elsewhere in the island chain isn't near as offbeat, it is as diverse. Overflowing bursts of bougainvillea, shimmering waters, and mangrove-lined islands can be admired throughout. The one thing most visitors don’t admire much in the Keys are their beaches. They’re not many, and they’re not what you’d expect. The reason? The coral reef. It breaks up the waves and prevents sand from being dumped on the shores. That’s why the beaches are mostly rough sand, as it’s crushed coral. Think of it as a trade-off: the Keys have the only living coral reef in the United States, but that reef prevents miles of shimmering sands from ever arriving.

In season, a river of traffic gushes southwest on this highway. But that doesn’t mean you can’t enjoy the ride as you cruise along the islands. Gaze over the silvery blue-and-green Atlantic and its living coral reef, with Florida Bay, the Gulf of Mexico, and the backcountry on your right (the Keys extend southwest from the mainland). At a few points the ocean and Gulf are as much as 10 miles apart; in most places, however, they’re from 1 to 4 miles apart, and on the narrowest landfill islands they’re separated only by the road.

While the views can be mesmerizing, to appreciate the Keys you need to get off the highway, especially in more developed regions like Key Largo, Islamorada, and Marathon. Once you do, rent a boat, anchor, and then fish, swim, or marvel at the sun, sea, and sky. Or visit one of the many sandbars, which are popular places to float the day away. Ocean-side, dive or snorkel spectacular coral reefs or pursue grouper, blue marlin, mahimahi, and other deepwater game fish. Along Florida Bay's coastline, kayak to secluded islands through mangrove forests, or seek out the bonefish, snapper, snook, and tarpon that lurk in the shallow grass flats and mangrove roots of the backcountry.

With virtually no distracting air pollution or obstructive high-rises, sunsets are a pure, unadulterated spectacle that each evening attract locals and visitors to any waterfront.

The Keys were only sparsely populated until the early 20th century. In 1905, however, railroad magnate Henry Flagler began building the extension of his Florida railroad south from Homestead to Key West. His goal was to establish a Miami–Key West rail link to his steamships that sailed between Key West and Havana, just 90 miles across the Straits of Florida. The railroad arrived at Key West in 1912, and remained a lifeline of commerce until the Labor Day hurricane of 1935 washed out much of its roadbed. The Overseas Highway, built over the railroad's old roadbeds and bridges, was completed in 1938.