In 1897, the explorer and amateur scientist Hugh de Laussat Willoughby climbed into a canoe and embarked on a coast-to-coast expedition of the Florida Everglades, a wilderness then nearly as vast as the peninsula itself and as unknown, he wrote, as the “heart of Africa.”

Willoughby and his guide were the first non-Native Americans to traverse the Everglades from the Gulf of Mexico to the Atlantic Ocean, and Willoughby’s meticulous notes, charts and water samples would form the basis of scientists’ historical understanding of the legendary “river of grass.”

Now a new expedition has retraced his trek, with the goal of measuring the impact of modern humanity on a watershed that today is among the most altered on Earth and responsible for the drinking water of some 12 million Floridians. The expedition also commemorates the 75^th anniversary of Everglades National Park, which was dedicated on Dec. 6, 1947.

“We think we will see the full spectrum, from one of the most remote parts of the continental United States to one of the most urbanized parts of the United States—all in one watershed, all in one trip,” said Harvey Oyer, co-leader of the four-member expedition and the author of a series of children’s books about the historical Florida frontier. “That, I think more than anything else, will illustrate humanity’s impact from the time of Willoughby to today.”

Willoughby’s thorough work provides a tantalizing opportunity to compare conditions in the Everglades then and now. Traveling the region’s rivers and canals over six days and some 130 miles, Oyer and the team drew water samples from the same spots as Willoughby, according to coordinates he documented, sometimes from some of the most remote and hard-to-reach parts of the subtropical region.

The water samples are being analyzed at the University of Florida for the same constituents that Willoughby examined, such as magnesium and sulfates, along with nutrients now known to affect the Everglades like phosphorus and nitrogen. The samples are also being tested for modern pollutants like microplastics, perfluoroalkyl and polyfluoroalkyl substances (PFAS), pesticides and pharmaceuticals. It will be a few months before the analysis is complete. The team wrapped up its trip on Nov. 2.

At the time of Willoughby’s expedition, the Everglades were mostly an unexplored, unmapped expanse of very inhospitable terrain characterized by unrelenting heat, mosquitoes and marshy prairies of sawgrass sharp enough to cut the skin. Now viewed as a vital ecosystem for the region’s drinking water and dozens of threatened and endangered species, its wetlands were then widely regarded as a worthless swamp and were known only to the Seminole people and their Calusa predecessors. Willoughby completed his expedition right before Henry Flagler’s railway system would link communities along the peninsula’s east coast, putting Florida on a path from frontier state to the country’s third-most populous of today. 

Willoughby wrote later: “It may seem strange, in our days of Arctic and African exploration, for the general public to learn that in our very midst, in one of our Atlantic coast states, we have a tract of land one hundred and thirty miles long and seventy miles wide that is as much unknown to the white man as the heart of Africa.” 

Today the Everglades, which begin in central Florida with the headwaters of the Kissimmee River and stretch to the southernmost tip of the peninsula, remain the world’s largest subtropical wilderness. The region’s watershed, however, has been drained to a fraction of its size. While the drainage has made modern Florida possible, with the vast construction of some of the most complex water management infrastructure in the world, it has also led to a cascade of environmental problems, perhaps most notably chronic blooms of toxic algae.

The watershed has been the focus of decades of bitter litigation over its water quality and a multibillion-dollar restoration effort, one of the most ambitious of its kind in human history. The restoration will take many decades to complete, but the water quality in Everglades National Park has improved vastly since the initial lawsuit was filed in the 1980s. The park’s water quality now meets or exceeds federal and state requirements, according to the South Florida Water Management District, the state agency overseeing Everglades restoration.   

The modern Willoughby Expedition, as it is called, began in Everglades National Park at the mouth of the Harney River in the Gulf of Mexico, where the relatively untouched environment would have been similar to what Willoughby experienced. The project’s team, paddling the entire way in canoes, also took note of egg clusters left by apple snails, the sole food of the endangered bird known as the snail kite. To guard against the razor-sharp sawgrass, the team members covered themselves completely and wore gloves like what butchers wear, Oyer said.

“We still had some sawgrass cuts,” he said. “We, not intentionally, just the way it worked out, wound up in sawgrass over our heads, completely surrounding us for probably 10 hours, not consecutively but cumulatively, including four or five hours of it at night, which was not the intention, of course. We hadn’t reached our scheduled destination.”

Within a few days, though, the environment transformed radically as the team reached well into what is now Miami. As its members approached the urban jungle, navigating a series of canals dug for drainage from the Everglades, the water quality went from pristine enough to drink to littered with garbage like Styrofoam and plastic, signaling the high level of microplastics that water testing is likely to detect.

The trip ended in downtown Miami, at the mouth of the Miami River. Charlie Arazoza, who served as the expedition’s navigator, grew up in the Everglades and remains an avid paddler of the river of grass. “I’ve spent a lot of time in the Everglades,” he said, “but for once I finally got to string it all together.”

“It’s really cool to put these, all these historical waterways, together into one trip,” he said. “It’s like stringing pearls.”