Old Seven Mile Bridge Trailhead (Marathon, MM 47)

Outdoors

A 1,300-foot boardwalk through mangroves -- rebuilt after Hurricane Irma -- is named for a wheelchair-using local teacher who spent her life fighting Keys overdevelopment; today it leads to one of the only wave-free, kid-safe wading beaches on the whole Overseas Highway.

Outdoors

A short climbing trail up the remains of the 1912 Bahia Honda Bridge -- the hardest span Flagler's crews ever built, over the deepest channel in the Keys -- dead-ends in open air where a section was removed, with panoramic Atlantic-on-one-side, Gulf-on-the-other views and three beaches (widely called the best natural sand in the Keys) at its base.

Nature

A former quarry pit is now the largest body of freshwater in the entire Florida Keys -- and the covered observation platform 225 feet from the parking lot is the single best spot in the refuge to see a wild alligator, Key deer, turtles, and wading birds from one stop.

Nature

A 63-acre wild hammock hides a bird-rehab hospital, Calusa and shipwreck-era pirate history, and the last known Bahamian-style pioneer house in the Keys, all a five-minute walk from US-1 -- genuinely the Middle Keys' deepest single stop for both nature and history in one ticket.

Outdoors

The largest undeveloped stretch of land left between Key Largo and Big Pine Key -- a 1.5-mile trail through a rare rockland hammock with one of the largest thatch-palm stands in the US ends at a bench overlooking the flat, silvery expanse of Florida Bay.

Outdoors

Six-plus miles of mostly paved, bike-and-wheelchair-accessible trail wind through one of the largest surviving tracts of West Indian tropical hardwood hammock left in the US -- a shady, buggy, genuinely wild counterpoint to the open-water bridge driving on either side of it, home to 84 protected species.