Like a gigantic real-world game of connect-the-dots, the Overseas Highway skips from island to island through the Florida Keys, with 42 bridges linking some 30 islands of this 400-plus-island archipelago.
Sure, you can fly directly into Key West or the mid-Keys hub of Marathon, but that almost feels like cheating—there’s something intriguing about following that highway all the way through this 150-mile-long (242km) string of islands, like pearls in a necklace.
Built in 1938 to replace Henry Flagler’s railroad (which had been destroyed by a hurricane—that’s South Florida for you), the Overseas Highway is a jumping-off point for the Keys—most islands are still accessible only by boat, many of them unpopulated. Divers, snorkelers, sport fishermen, and kayakers may depend on the highway to get here—addresses in the Keys generally refer to U.S. 1 mile markers—but as soon as possible they leave its inevitable traffic jams behind and get onto the water. And the farther you go, the more exotic and unspoiled the Florida Keys still seem.
Many divers get no farther than the first large island off the mainland, Key Largo (originally Rock Harbor, it was renamed after the 1948 Humphrey Bogart film), where John Pennekamp Coral Reef State Park protects part of the only living coral reef in the continental United States. Glass-bottom boat tours are the classic way for nondiving tourists to view this undersea preserve’s shallow waters, populated with 40 species of coral and more than 650 species of fish. For a more serene experience, rent a canoe to paddle through Pennekamp’s narrow mangrove channels and tidal creeks. Less well-known is Key Largo’s other gem, Dagny Johnson Key Largo Hammock Botanical State Park, a fascinating remnant of West Indian tropical hardwood hammock (which is an elevated piece of land above a marsh), created by seeds dropped by migratory song-birds flying north from the Caribbean. Over 6 miles (9.7km) of nature trails display 84 protected species of plants and animals, including several rare birds (white-crowned pigeons, mangrove cuckoos, black-whiskered vireos) and an incredible number of butterflies. You can also get close to nature at the Florida Keys Wild Bird Center in Tavernier, a much-loved sanctuary for injured local birds where you can hike a nature trail; watch pelicans, cormorants, herons, and roseate spoon-bills feeding in the shallows; and learn about the Keys ecosystem.
A scrum of marinas and charter-boat operations tells you that sport fishing is king in the next community, Islamorada (actually four islands: Plantation Key, Windley Key, Upper and Lower Matecumbe Keys). From Islamorada, take a ferry or rent a power-boat to visit Lignumvitae Key, another rare fragment of virgin tropical forest. Named for the lignum vitae (“wood of life”) trees found there, it still has several lush hammocks which botanists have painstakingly restored so that only truly native species live here. Don’t miss the splendid botanical gardens surrounding the park’s main structure, the coral rock Matheson House, built in 1919. Past Islamorada, Long Key—once Henry Flagler’s exclusive fishing retreat—is almost entirely occupied by the 965-acre (391-hectare) Long Key State Recreation Area, sited atop the remains of an ancient coral reef. Here you can hike or canoe through several distinct habitats, including beaches where sea turtles nest in season (humans can observe from a respectful distance).
Once you cross Long Key, you’ve reached the somewhat more laid-back Middle Keys, with its main town of Marathon (covering Vaca, Fat Deer, and Grassy Keys). Sun worshipers flock to Sombrero Beach, one of the few really good beaches in the Keys, but for nature lovers the highlight is the Crane Point Nature Center (Mile Marker 50), a 64-acre (26-hectare) property containing what is probably the last virgin thatch-palm hammock in North America. The visitor center has some wonderful exhibits on local ecology; walking trails meander through several habitats, from a butterfly meadow to a freshwater pond to stands of red, white, and black mangroves. For a glimpse of vintage Keys life before the highway arrived, take a ferry from Knight’s Key (Mile Marker 47) to historic Pigeon Key, a palm-fringed 5-acre (2-hectare) island under the old Seven-Mile Bridge where Flagler’s railroad workers lived in modest yellow wood-frame cottages. While cars today soar over the water on its modern replacement, the original Seven-Mile Bridge—itself a major engineering feat for its time—has become an alternative route for cycling and other “green” modes of transport; if you have time, you can walk the 21⁄4 miles (3.5km) over it to Pigeon Key.