Sombrero Beach (Marathon, MM 50)

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.

Outdoors

Anastasia limestone shore that erupts in 50-foot plumes at high seas; Nature Conservancy preserve.

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.

Outdoors

Fossil-rich beach in Venice known for shark-tooth hunting; sift the drift line for prehistoric teeth eroding from offshore Miocene deposits.

Outdoors

Audubon's 2.25-mile boardwalk through the largest old-growth bald-cypress stand in North America, near Naples.