Key Biscayne Boat Tour

Ninety-five percent of Biscayne National Park lies underwater. Its 172,971 acres protect four joined ecosystems: the shallow bay, a mangrove shoreline, the northernmost Florida Keys, and the upper reach of the world's third-largest coral reef tract. Congress made the area a national monument in 1968, after plans for a causeway-linked industrial city and an oil refinery nearly remade the shoreline. National park status followed in 1980. Key Biscayne Boat Tour tours cross all four zones in one morning, which is why the water, not the land, carries the visit. The bay's strangest architecture stands on pilings. Stiltsville began in the 1930s as a loose colony of fishing shacks, bait stands and gambling barges raised above the flats north of Soldier Key. Twenty-seven structures stood at its peak. Hurricane Andrew left seven in 1992, and those seven now survive under federal stewardship, their roofs bleached, their ladders dropping into two feet of turquoise water. Boca Chita Key answers them with a 65-foot ornamental lighthouse, built in the 1930s by the industrialist Mark Honeywell for a wife who, by most accounts, disliked the island. The living record is quieter and older. Seagrass meadows here rank among the largest in the hemisphere, grazing ground for manatees and green sea turtles and nursery for the spiny lobster fishery that supplied Miami's docks for a century. Elliott Key, the park's largest island at roughly seven miles, carries tropical hardwood hammock — mahogany, gumbo limbo, wild lime — and the endangered Schaus' swallowtail butterfly. American crocodiles nest along the southern shallows. Six documented wrecks, from an iron-hulled nineteenth-century steamer to a mid-century cabin cruiser, form the Maritime Heritage Trail, the only underwater archaeological trail in the national park system. That layering explains the park's current pull. Few of Miami's waterfront landmarks can be read from a road; almost all of them can be read from a hull. Today the Key Biscayne Boat Tour tour routes trace the same geography the 1968 campaigners defended — mangrove to seagrass, stilt house to reef — and the 1825 Cape Florida Lighthouse still marks the northern gate.