The River of Grass moves six inches per hour. Marjory Stoneman Douglas named it that in 1947, the year President Truman dedicated 1.5 million acres of South Florida wetland as the nation's third national park. What appears as solid marsh is a slow-motion sheet flow 60 miles wide, draining Lake Okeechobee toward Florida Bay at a gradient so slight surveyors need weeks to measure it. The sawgrass prairie hides a topography of solution holes and limestone ridges, each elevation shift of six inches creating a distinct plant community: hardwood hammocks on the high ground, sloughs in the troughs, and along the coast a labyrinth of red mangrove tunnels where saltwater meets fresh. Everglades mangrove airboat tours operate from the park's eastern boundary near Homestead, where State Road 9336 enters the preserve. The flat-bottomed vessels draw four inches and ride an aircraft propeller, designed in the 1930s by local frogging crews who needed to cross sawgrass without a submerged drive shaft. A 454-cubic-inch engine pushes the hull across water too shallow for an outboard, the elevated seat positioning passengers above the grass line for sight lines across the marsh. The route depends on water level: winter's dry season exposes the marl flats and concentrates wading birds at shrinking pools; summer's six-month wet season floods the sloughs and pushes alligators into the mangrove fringe. The park protects 67 threatened species. American crocodiles nest on coastal berms. Florida panthers hunt the pinelands at dawn. Roseate spoonbills probe tidal mudflats with spatulate bills, filtering amphipods in water one inch deep. Wood storks, the only stork native to North America, forage in receding pools where prey fish become trapped, and the species' breeding success correlates directly to the timing of the dry-down. The mangrove estuaries function as nursery habitat for juvenile tarpon, snook, and red drum, the tangled prop roots breaking current and sieving plankton. An estimated 220 fish species use the estuary at some life stage, and the root structure accretes sediment, building land at a rate of one vertical inch per decade in microtidal settings. Florida's mangrove airboat tour tickets include the standard seven-day vehicle pass, valid at all park entrances. Non-U.S. residents pay an additional hundred-dollar per-person fee, a surcharge implemented in 2024 to fund exotic species removal. The park operates continuously, gates unstaffed after sunset. Peak visitation occurs January through March, when northern breeding populations of warblers and vireos overwinter in the hammocks and temperature averages 77 degrees. August heat and afternoon thunderstorms suppress crowds, but water levels peak and wildlife disperses across the flooded prairie, making sightings less predictable for those booking an Everglades wildlife expedition.