First-time visitors to the Florida Keys comment almost immediately on the island chain’s unique laid-back atmosphere that seems to be a world away from big cities and theme parks.

It’s the kind of ambiance that lured renowned novelist Ernest Hemingway to reside in Key West throughout the 1930s, when he drew creative inspiration from the subtropical island’s lush environment and colorful residents. There he penned some of his most famous works including “For Whom the Bell Tolls,” “To Have and Have Not” and “The Snows of Kilimanjaro.”

A necklace of islands that begins just south of Miami, the Florida Keys are connected by the Overseas Highway’s 42 bridges — one almost seven miles long — over the Atlantic Ocean, Florida Bay and the Gulf of Mexico. In 2009, the famed highway was designated an All-American Road, the highest recognition possible under the National Scenic Byways program established by the United States Congress.

The Florida Keys are divided into five regions: Key Largo, Islamorada, Marathon, Big Pine and the Lower Keys, and Key West. Each region has its own special flavor, attractions including historic museums, flora, fauna, restaurants featuring local seafood and other specialties, fishing, diving, watersports and boutique-type shopping experiences.

Vistas of the Keys are dominated by emerald-green harbors, turquoise seas, nodding palms, rustling pines and olive-green mangroves. Sharing this eco-paradise are white herons, roseate spoonbills, pelicans, sea gulls, ospreys and countless underwater creatures.

The coastal waters of the entire 125-mile island chain, including its shallow water flats, mangrove islets and coral reefs, have been designated the Florida Keys National Marine Sanctuary.

Key Largo
The longest island of the Keys chain, Key Largo shares its name with the famous movie starring Humphrey Bogart and Lauren Bacall — portions of which were filmed there. Bogart’s Key Largo connection still is evident today as visitors can see the African Queen, the actual boat he skippered in the movie of the same name.

But Key Largo’s star attraction is John Pennekamp Coral Reef State Park, the first underwater preserve in the United States, incorporated within the Florida Keys National Marine Sanctuary. These protected areas feature more than 50 varieties of delicate corals and more than 600 species of fish.

Pennekamp Park, located at mile marker (MM) 102.5, is open from 8 a.m. to sunset, and offers a variety of water-related activities including scuba, snorkeling and glass-bottom boat excursions to the coral reef. Key Largo also boasts a number of off-park dive charter companies that conduct dive sojourns — and a few even feature underwater weddings, where the entire wedding party gets wet as the bride and groom tie the knot.

After the wedding reception, newlyweds can choose to remain submerged for their honeymoon at an underwater hotel in Key Largo, where people can spend the night with full amenities among the marine life of the Keys.

Key Largo also is home to the Spiegel Grove, a retired U.S. Navy ship that is one of the largest vessels in the world ever purposely scuttled to create an artificial reef.

Islamorada
Islamorada is the centerpiece of a group of islands called the “purple isles.” Legend says Spanish explorers named the area from “morado,” the Spanish word for purple — either for the janthina janthina, a violet sea snail found in the subtropical waters, or for the purple bougainvillea flowers in the area.

Known as the Sport-Fishing Capital of the World, Islamorada is heralded for its angling diversity and features the Keys’ largest fleet of offshore charter and shallow-water “backcountry” boats.

The Keys boast more sport-fishing world records than any other fishing destination on the planet, according to the International Game Fish Association. Here anglers can find sailfish, marlin, dolphin (the fish, not the mammal), kingfish, snapper, barracuda and grouper in the ocean. Tarpon, bonefish, permit, redfish and other species thrive in the shallow coastal waters.

Numerous high-profile figures, including past U.S. presidents and British royalty, have visited Islamorada to take part in the world’s best sport fishing and to compete in acclaimed fund-raising fishing tournaments.

Marathon
Home to the Seven Mile Bridge, Marathon is a renowned boating destination and is centrally located at the heart of the Florida Keys between Key Largo and Key West.

Marathon also is home to Crane Point, a 63-acre land tract that is one of the most important historical and archaeological sites in the Keys. This ecological and cultural treasure contains evidence of pre-Columbian and prehistoric Bahamian artifacts, and was once the site of an entire Indian village. Attractions include an intriguing museum, nature trails and the historic Adderley House.

Marathon also features Dolphin Research Center, one of five Keys facilities that provide visitors an opportunity to swim and interact with the intelligent mammals. Reservations for dolphin encounter programs must be made in advance, and strict guidelines govern the interaction sessions for the benefit of human and dolphin participants.

A drive across the modern-day Seven Mile Bridge, (actually 6.79 miles long), the longest segmental bridge in the world, leads to the Lower Keys. But visitors shouldn’t pass up the chance to explore Pigeon Key, a small island below the middle of the Old Seven Mile Bridge, that is accessible from a visitor center at the west end of Marathon.

Reachable by ferry,Pigeon Key once housed the workers who built Henry Flagler’s historic Over-Sea Railroad in the early 1900s. While the rest of the Keys have evolved with the years, this tiny island has remained essentially unchanged and is now a national historic treasure complete with a museum chronicling the railroad’s construction.

Big Pine Key and the Lower Keys
The sheer sweep of the Straits of Florida and the Gulf of Mexico is readily seen from the Bahia Honda Bridge. Bahia Honda State Park, whose beach was named one of the top 10 in the United States by several travel studies, is a prime example of the Lower Keys’ pristine beauty.

The Lower Keys are noted for Looe Key Reef, rated by many as among the most spectacular shallow-water dive sites. To the west of Looe Key, the 210-foot island freighter Adolphus Busch Sr. rests on the ocean floor as an artificial reef, providing additional habitat for marine species as well as an intriguing site for divers.

Big Pine Key also features a national refuge for miniature Key deer, tropical forest and even a few alligators. Popular nature tours, many by kayak, offer unforgettable opportunities to view the unique flora and fauna of this tranquil natural area of the Keys.

Key West
Key West is the final stop on the Overseas Highway, where the land ends and meets the sea amid 19th-century charm and contemporary attractions. Continental America’s southernmost city, situated closer to Cuba than to Miami, is characterized by quaint palm-studded streets, century-old gingerbread mansions and a relaxed citizenry of self-styled “conchs” (pronounced konks).

It has been said that the idiosyncratic architecture and laid-back atmosphere of this small, 2-by-4-mile island probably have nurtured the talents of more writers per capita than any other city in the country. Literally scores of published authors reside in Key West either full- or part-time, and the island’s flourishing artistic community is evidenced by the many galleries exhibiting artwork in varying styles and mediums.

Key West is home to other treasures as well. Longtime resident Mel Fisher, a legendary treasure hunter who died in 1998, recovered approximately $450 million in gold and silver from the Nuestra Señora de Atocha, a 17th-century Spanish galleon that sank 35 miles southwest of Key West. Fisher, who spent 16 years searching for the shipwreck, established the Mel Fisher Maritime Museum where visitors can view and learn about the riches of the Atocha and other area shipwrecks including the galleon Santa Margarita.

At day’s end in Key West, crowds gather at Mallory Square to experience the nightly “sunset celebration,” a tradition that locals share with visitors. While musicians, jugglers, acrobats and other performers provide entertainment, the sun sinks slowly below the horizon as sunset cruise boats sail by in Key West Harbor.

Dining opportunities in the island city are as enticing as the sunset. Key West’s culinary influences and offerings are diverse, but most restaurants feature great area seafood such as shrimp, Florida lobster, local fish and stone crab claws. A slice of Key lime pie, the Keys’ signature dessert, is a heavenly end to a meal.

The nightlife in Key West can be lively and exciting. The “Duval Crawl” is a popular phrase used to describe fun-seekers’ evening jaunts up and down the island’s main street to sample numerous taverns and entertainment offerings.

For more culturally oriented visitors, theater is available at several playhouses, and diverse musical organizations offer periodic concerts.

And when the Keys experience concludes, visitors can fly from Key West International Airport directly to international hubs in Miami, Fort Lauderdale, Orlando or Tampa, Fla., and Atlanta, Ga. — as well as to Florida’s Fort Myers and West Palm Beach. Airlines serving Key West include AirTran, American Eagle, Delta Connection, United Airlines, US Airways, Cape Air and others.

Florida Keys Marathon Airport, located at MM 52 bayside, is served by several charter airlines and is home to fixed-base operators that offer private aircraft accessibility.