At dinner in Miami Beach the night before I picked up the rented Toyota and drove down U.S. 1, my friend Laura, Florida born and bred, explained how she knew when she'd crossed the border into Keys territory: "You walk into a bar where you've never been in your life. If everyone there treats you as if you've been closing the place every night for the last eight years, you're in the Keys."

Over a plate of conch fritters on the deck at Alabama Jack's just north of Key Largo, I decided to test Laura's theory. I sidled up to the bar and set my iced tea down next to a line of empty longneck Budweisers. The iced tea, alas, was the best I could do. I still had about 75 miles of slow, two-lane driving before reaching my destination, Big Pine Key.

It took about 10 seconds for the bartender to say a hearty hello, then another 15 for the Bud drinker, a sunburned fellow in a tropical shirt, shorts and Tevas, to introduce himself. In a minute or so, we were discussing his plans to open an authentic bagel bakery south of Key Largo.

"Tourists come down here from the north, and they want bagels, real New York-style bagels, for breakfast and they can't get them, so you can see the potential here," he said.

A curious New Yorker could not resist asking him where he had learned so much about bagel baking.

"I ran a bagel operation up north," he said. "In Boulder, Colo."

It took a while to get back on the road because of the corollary to Laura's theory -- you know you're in the Keys when it takes twice as long as usual to say goodbye in any bar. Driving again, through walls of thick mangrove that suddenly parted to reveal flat roadside clusters of motels, shopping malls, and souvenir and bait shops, I counted the mile markers backward (Key West is mile zero), and thought about the Keys' legendary anything-goes bonhomie. I hadn't expected to find much of it as I planned to spend four days there in early February.

Jimmy Buffett has practically made a cliche of the laid-back, end-of-the-road lifestyle, and whatever aspects of Keys culture he might have missed have been scooped up for atmosphere by novelists like Elmore Leonard.

Thanks to the exposure, tourism (and prices) in the Keys had skyrocketed since my last visit in 1979. I worried that the Keys might have turned into a parody of itself, a theme park called Margaritaville. So I designed my trip to cut costs and avoid crowds. Because February is high season, I stayed in the Lower Keys, rather than in Key West. They stretch southward from the spectacular Seven-Mile Bridge and are within 40 minutes' drive of the city, close enough to visit for a day's sightseeing.

I found other reasons to like the Lower Keys as I investigated further. They are a trove of nature preserves, on land and sea. I set my sights on Big Pine Key, where little Key deer, an endangered species, were said to roam freely. From Big Pine I could kayak in the protected waters of adjacent Coupon Bight, which was filled with mangrove clusters that sheltered innumerable species of birds. The key was about a half-hour boat ride from great snorkeling in the Looe Key National Marine Sanctuary.