The Everglades, a vast wetland at the southern tip of Florida, is often described as a swamp, but it is technically a slow-moving river. The area is a complex ecosystem shaped by a unique set of conditions, and its history includes both natural phenomena and human intervention.

The region is the only place on Earth where American alligators and American crocodiles share the same habitat. Alligators live in freshwater marshes while crocodiles live in the salty mangrove coast. An estimated 200,000 alligators live in the system, while the crocodile population, which dropped to 150 in the 1970s, has recovered to about 2,000. Both can be found within an hour of downtown Miami.

The ecosystem has also been affected by invasive species. Burmese pythons, free in the Everglades since the 1990s, are now estimated to number between 100,000 and 300,000. Their presence has led to significant declines in native mammal populations, with road surveys from 2012 finding raccoon sightings down 99.3% and opossums down 98.9%. The pythons have no natural predators in Florida, and removal efforts, such as a team pulling 748 of them from the marsh in July 2025, have had limited impact.

The system is driven by Lake Okeechobee, a 730-square-mile lake that is larger than New York City and Los Angeles combined, yet averages only 9 feet deep. It is the second-largest freshwater lake entirely within the lower 48 states.

In the 1890s, the most valuable commodity in the area was bird feathers, which were sold for about $32 an ounce, roughly twice the price of gold, for use in feathered hats. Hunting reduced Florida’s wading bird population from about 2 million to half a million. In 1905, a warden named Guy Bradley was shot dead while protecting the birds, and his death contributed to the passage of the Migratory Bird Treaty Act of 1918.

For roughly 2,000 years, the Calusa people ruled southwest Florida and the Everglades coast without ever planting a crop. They engineered canals and walled fish traps to harvest estuaries, built towns on oyster shell mounds, and paddled dugout canoes as far as Cuba.

The area south and west of the Everglades contains the largest mangrove forest in the continental United States. Covering more than 550 square miles, it holds over 90% of all mangroves in Florida. The roots store carbon and help break storm surge. In 1992, Hurricane Andrew flattened 70,000 acres of the forest in a single night.

In the 1960s, Aerojet General built two silos 5 miles from the national park to test the AJ260, the most powerful solid fuel rocket motor ever constructed. The motor, nearly 22 feet across, produced 5.4 million pounds of thrust. After NASA chose liquid fuel in 1969, the project was abandoned, and one of the motors was left in its silo, where it remains.

By around 1970, the Florida panther population, the only cougars left east of the Mississippi, had collapsed to roughly six animals. Today, there are between 120 and 230, living in and around the Everglades and Big Cypress. A single panther requires about 200 square miles of range, and the biggest killer of the panthers is cars.

The Everglades snail kite, a hawk that feeds almost exclusively on apple snails, was down to a few hundred in the early 2000s. An invasive species, the island apple snail from South America, arrived and provided a larger food source. Over about a decade, the kites measurably grew beaks and bodies roughly 10% larger to crack the bigger shells, and the population climbed back toward 3,000.

After the Cuban missile crisis, the US Army built a missile base, HM69, inside Everglades National Park. It was operational in 1964, armed with Nike Hercules missiles designed to carry nuclear warheads with yields up to 40 kilotons. The base shut down in 1979, and its buildings still stand, open for ranger tours.

Next to the park lies Big Cypress National Preserve, covering 729,000 acres. Created in 1974, it was the first national preserve in US history, established in part to stop a plan for a jetport in the swamp. The name refers to the reach of the swamp, not the size of the trees, which are often small or dwarfed.

The ghost orchid grows in the strand swamps west of the Everglades. It has no leaves and almost no visible stem, only a single white bloom suspended against the dark. The orchid photosynthesizes through its flattened green roots. Fewer than 2,000 survive in the US, and only 5 to 10% flower in any given year.

The American alligator, removed from the endangered list in 1987, plays a key role in the ecosystem. During the dry season, gators dig out depressions in the limestone, which hold water year-round. These gator holes become the last open water for miles, providing refuge for fish, turtles, and frogs, and attracting herons and egrets. The gators are keeping the food web alive.

Scattered across the marsh are thousands of tree islands, patches of hardwood forest that rise a foot or two above the water. They support species that cannot grow in the open marsh and hold two to three times the biodiversity of the surrounding sawgrass. Some of these islands were helped by native peoples who lived on them, leaving shell, bone, and refuse that enriched the soil.

The sawgrass that covers two-thirds of the Everglades is technically a sedge, not a grass. It has ruled the landscape for at least 5,000 years. The edges of its blades carry rows of tiny backward-facing teeth, which can cut.

In 1881, Philadelphia manufacturer Hamilton Disston bought 4 million acres of Florida for 25 cents an acre. It was the largest single land purchase by one person in American history. His plan was to drain the Everglades for farmland. He dug canals for 6 years, but the summer rains swallowed the dry ground back. The state declared the drainage a failure in 1887, and Disston died bankrupt in 1896.

When the Tamiami Trail opened in 1928, it created a dam across the Everglades. The road blocked the slow southern flow of water, causing water to stack up on the north side while the park to the south dried out. Undoing this has cost around $100 million in bridge and roadbed removals, and the final stretch is still under construction.

On the edge of the swamp sits the smallest operating post office in the US. The Ochopee station measures 61.3 square feet and was originally an irrigation pipe shed on a tomato farm. When a fire destroyed the town’s general store in 1953, the shed was pressed into service. It is still running more than 70 years later.

The Kissimmee River once wound 100 miles down to Lake Okeechobee through a flood plain 2 miles wide. Between 1962 and 1971, the Army Corps of Engineers straightened it into a 56-mile drainage canal, draining 50,000 acres of wetland. Starting in 1999, crews backfilled 22 miles of the canal and restored 44 miles of the old river. By 2021, the work was done, and 159 bird species had returned.

Everglades National Park, dedicated in 1947, was the first national park in America protected for its biodiversity rather than for features like canyons or mountains. At 1.5 million acres, it is the largest subtropical wilderness in the country and holds UNESCO World Heritage status, a wetland of international importance listing, and biosphere reserve status.

The United States fought three wars to remove the Seminole and Miccosukee peoples from Florida. The groups withdrew deep into the Everglades, where soldiers could not navigate. The Second Seminole War, from 1835 to 1842, ended not with surrender but with an American officer declaring it over. A few hundred people held out, and no peace treaty was ever signed. Their descendants received federal recognition as the Seminole tribe in 1957 and the Miccosukee in 1962 and live in the area today.

On September 16, 1928, a hurricane drove Lake Okeechobee over its earthen rim. A wall of water swept across the farming towns below, killing at least 2,500 people, most of them black migrant farmworkers. In response, the state built the Herbert Hoover Dike, 85 miles of earth around the lake. It stopped the floods but separated the lake from the Everglades it had fed for 5,000 years.

Florida Bay, at the foot of the Everglades, holds one of the largest continuous sea grass meadows on Earth. It depends on fresh water from the Everglades. When that flow failed in the summer of 1987, the bay became hypersaline and the sea grass died in a collapse scientists had not recorded elsewhere.

The Everglades evolved with very low natural phosphorus levels, around 5 to 10 parts per billion. Fertilizer from upstream farms raised levels past 200 parts per billion in places. The native sawgrass is replaced by cattail, which looks green but is silent of fish and birds.

Every few summers, Lake Okeechobee blooms with toxic blue-green algae. In 2023, a bloom covered more than 400 square miles. The toxins have been linked to liver disease and neurological illness. When the lake rises, the Army Corps releases the water east and west into coastal rivers. In 2018, a combined algae and red tide disaster tied to those discharges cost Southwest Florida tourism $2.6 billion.

Fire is a natural part of the Everglades, clearing out woody growth and resetting the open sawgrass. Wet season fires sweep across the surface, but dry season fires can burn down into the peat, incinerating soil that took thousands of years to form.

The state of Florida advises against eating largemouth bass from nearly a million acres of the Everglades. The fish can carry mercury at over 1.5 parts per million, among the highest levels measured anywhere. Sulfate running off sugarcane fields feeds bacteria that convert mercury into methylmercury, which concentrates in fish.

A spongy mat of algae and microbes called periphyton carpets the marsh floor. It forms the base of the food web, builds the soil, and is so sensitive to pollution that scientists use it as an early warning signal. When phosphorus rises, the mat collapses within a season.

Sea level off South Florida has risen about 9 inches in the last century. Because the Everglades is nearly flat, the salt line has pushed roughly 4 to 5 miles inland. When salt hits freshwater peat, it kills the roots holding the soil together, causing the ground to drop and the marsh to drown.

The Comprehensive Everglades Restoration Plan, signed into law in 2000, is the most ambitious ecological repair project in human history. It spans the full 18,000-square-mile system with nearly 200 construction projects and a price tag above $16 billion. Decades in, it is still only partly finished. The plan involves rebuilding rivers, tearing out levees, and building reservoirs to re-time the flow of water across South Florida.

The Everglades sits on peat, a black soil built up over 5,000 years from dead sawgrass. It is the largest single body of organic soil on the planet. Peat only survives underwater. When drained, it oxidizes and burns away. Since drainage began, the Everglades has lost roughly 900 million tons of it.

The Everglades is the sole source of drinking water for Miami-Dade, Broward, Palm Beach, and Monroe counties, serving more than 5 million people. The Biscayne Aquifer, a shallow bed of porous limestone, is recharged by the marsh. Rising seas already threaten to push salt into it permanently.

A century ago, the Everglades held one of the greatest concentrations of birds in North America, with around 2 million wading birds in the dry season. Today, nesting birds in the southern Everglades are down about 93% from the 1930s, from roughly 265,000 to fewer than 20,000.

The Everglades is a literal river, running from Lake Okeechobee to Florida Bay. It is up to 60 miles wide and only inches deep, moving slowly across the peninsula, which tilts just 2 inches per mile. The water creeps south in a single sheet with no channel or banks.

In 1947, writer Marjory Stoneman Douglas named it the river of grass. The area is 18,000 square miles, a single living river running from a chain of lakes near Orlando to the sea. For 150 years, the Everglades was treated as a swamp to be conquered or saved, but it is a river so wide and slow it was mistaken for a swamp.