The old Seven Mile Bridge, which carried first the railroad and later US-1 over Pigeon Key between Marathon and Big Pine Key, was replaced in the early 1980s by a soaring new bridge that gives another batch of breathtaking ocean-to-gulf views. (The old bridge, which was seen in the Arnold Schwarzenegger/Jamie Lee Curtis movie True Lies, still stands below the new one but is now used as a very long fishing pier.)

The south end of the Seven Mile Bridge, near milemarker 40, marks the start of the Lower Keys, which are considerably less commercial than the others. The best of the Lower Keys is yours to enjoy at milemarker 36.5, where the entrance to Bahia Honda State Park (305/872-2353) leaves the highway behind and brings you back to the way the keys used to be: covered in palms and coastal hardwood hammocks, with white-sand beaches stretching for miles along blue-water seas. Facilities are limited to a few cabins (around $120 off season, $160 peak season), a general store, and a snorkel rental stand, but it’s a great place to spend some time fishing, beachcombing, sunbathing, or swimming in the deep, warm waters of the Atlantic Ocean or Gulf of Mexico. Camping (around $360 a night) is the best way to enjoy the sunset, sunrise, and everything in between.

From Bahia Honda, US-1 bends along to Big Pine Key, second largest of the keys and suffering from a bout of suburban minimall sprawl. Though it looks about as far from natural as can be, Big Pine Key happens to be part of the National Key Deer Refuge, set up to protect the increasingly rare key deer, the “world’s smallest deer” at around three feet tall. Some 800 key deer now live on the island.

The last big key before Key West is Sugarloaf Key, formerly full of pineapple plantations but now known for its Perky’s Bat Tower (MM 17), a national historic landmark alongside US-1. Built by a man named Perky in 1929, the 35-foot tower was designed to house a colony of bats, who were supposed to feast on the plentiful mosquitoes here; however, the bats stayed away, and the mosquitoes stayed put. Sugarloaf Key is also home to the wild Mangrove Mama’s (MM 20, 305/745-3030), a roadhouse tucked away south of the bridge. The seafood and key lime pie are as good as it gets, and there’s often live music in the evenings.