Great Falls has become a hotbed for talent in the world of competitive kayaking. Watch a group of daring athletes take the plunge through the Class V rapids on the Potomac River. (Ben Dorger and McKenna Ewen/The Washington Post)

For nearly four decades, kayakers have charged down the careening, foam-tipped rapids of Great Falls in multicolored groups of boats. And for nearly four decades, observers have called the police on them, reasoning that paddling a tiny boat through such treacherous waters must certainly be banned.

Kayaking through this section of the Potomac River is legal, however, if the paddlers enter in approved spots and have the appropriate equipment. But to be clear: No one without significant experience should attempt the dangerous, sometimes deadly, run.

The kayakers who paddle the Falls successfully have spent hours running smaller drops and piecing together specific skills — much like a musician must learn different techniques and notes before mastering a complex song — said one longtime Falls paddler and former Olympian. The Potomac River includes one of the steepest kayak runs in the world — 60 feet in 60 seconds. It drops 76 feet in less than a mile. There is a 20-foot drop and cascading rapids that rank in Class V and VI whitewater.

The rapids appear unrunnable and deadly, which they can be for anyone other than a top-level kayaker. But these athletes are. It takes a certain level of training and respect for the water to safely barrel down rapids with names like “Grace Under Pressure” and “Pummel.”

Few visitors to Great Falls realize the athletes flying down the rapids and emerging from the foam are not just reckless thrill seekers but national, world and Olympic competitors.

They are drawn to the sport by the outdoors, the scenic backdrop, the challenge and the adrenaline rush — a moment of suspension during which they are acutely aware of their surroundings while the mind remains free from intrusion .

“The D.C. area, as far as I’ve seen, is pretty much the biggest paddling community in the world,” said Jordan Poffenberger, the reigning world champion in canoe freestyle and a Fairfax native who attends George Mason University.

“No one ever thinks of D.C. as a paddling location, but there’s nowhere else you can have a whole mess of all types of boaters. . . . I don’t know if there’s anywhere else in the world like this.”

Cultivating a hotbed of talent in one sport requires a handful of factors falling together serendipitously. The Potomac, which rarely freezes over, provides year-round training in everything from kayak polo and flatwater racing to freestyle and extreme racing.

The 26th annual Great Falls Race brings 30 of the toughest boaters in the region to the Maryland side of the waterfalls Saturday. But the accessibility of the river and its features have attracted paddlers for nearly half a century.

The planner and the teacher

A chance encounter in the Landon School lunchroom in 1961 changed the fate of whitewater kayaking in the D.C. area.

Tom McEwan was 15 when he sat down across the table from classmate Wick Walker, who was telling stories about wading in water up to his knees during self-sufficient canoeing expeditions in Canada. McEwan was fascinated, and the two became quick friends and paddling buddies.

They would strap a canoe to Walker’s mother’s Pontiac and leave straight from school Friday for rivers in West Virginia or Pennsylvania. They wouldn’t return until right before their first class Monday and would wash off the mud and sweat in the school’s bathroom before changing into something that conformed to Landon’s dress code.

McEwan persuaded the headmaster to let them train for the Potomac Downriver Race to fulfill Landon’s athletic requirement. The high schoolers paddled so hard that at the finish, McEwan leaned over the side of the boat and threw up. The older racers laughed at their inexperience until they saw the times: McEwan and Walker, a pair of teens with little competitive experience, beat the national champions by three minutes.

More than five decades later, McEwan, 68, recalled the story on the banks of the river where he has spent much of his life.

Whitewater is one of the most dynamic places on earth. It’s constantly moving, changing and surging, and so is the sport. McEwan pushed the limits of the sport on the East Coast by being one of the first paddlers to navigate Great Falls. But his greatest contribution has been passing on knowledge and experience. He was — and still is — the teacher.

“Wick was the planner,” he admits, “and I was the one who went along with it and said, ‘Okay, let’s do things like running the Falls and take on these challenges.’ ”

If Walker was the instigator, McEwan’s younger brother by six years, Jamie, was the competitor. He made the 1972 Olympic team and brought home a bronze in whitewater slalom from Munich.

Jamie’s medal inspired the next generation. Davey and Cathy Hearn remember the exact moment they decided to pursue the sport competitively. They were driving down a dirt road in Montana, 2,000 miles from home on a trip with their father, when they heard news of Jamie’s medal over the radio.

The Hearn siblings returned home to Bethesda and amped up their training, eventually winning 24 ICF Canoe Slalom World Championship medals and competing in a combined three Olympics. Davey often paddled with Jon Lugbill, who was the first American to win a gold medal in the world championship and the only paddler to appear on a Wheaties cereal box.

Lugbill and David Hearn would train at slalom gates set up near Great Falls. Bethesda native Joe Jacobi, CEO of Team USA Canoe/Kayak and winner of a flatwater gold in the 1992 Olympics, remembers an afternoon he came to train on the gates as a 14-year-old and encountered the pair. Lugbill and Hearn told him to “get out on the river and have fun” instead of training.

“The highest level of the sport was very touchable,” Jacobi said. “There’s not a big fence between entry level and championship, and there’s a real lineage from generation to generation.”

Tom McEwan, who went on a six-week canoeing trip after failing to make the 1972 Olympic team, was planning expeditions with Walker. They wanted to figure out whether they could take their boats — and bodies — safely down waterfalls.

One evening in the summer of 1975, Walker, McEwan and a friend camped out on an island downriver and sneaked out at dawn to run Great Falls before rangers could catch them.

They ran each “line” three times to prove that it was possible and “to keep themselves honest,” McEwan said. They ran the Falls once or twice a year but did not tell the paddling community what they had done until five years later.

‘Doing what we know how to do’

Not all kayakers that paddle Great Falls learned directly under McEwan, but a majority have been influenced at some point by his teaching and innovation. That includes Jacobi and Geoff Calhoun, a former U.S. Wildwater Team member and four-time national champion who was taught by McEwan’s son. Pablo McCandless, who competed in the 2008 Olympics for Chile, learned from McEwan, as did Jason Beakes, a seven-year USA Kayak Team member and six-time winner of the Great Falls race, and Elliot Weintrob, a 1992 Olympian, among others.

Those paddlers have gone on to teach the newest generation of junior team members and high schoolers. They’re part of “a whole scene that goes back through a lot of history,” one that has churned out talent looking to “be as good as our heroes,” Calhoun said.

The paddlers that run the Falls are doctors, students, Olympians and businessmen, ranging in age from 40-year-olds to teens. They hoist highlighter-colored boats over their shoulders and hike to the top of the Falls, where they pop their kayaks into the murky green water.

At several points the waterfalls are completely white — moving, rushing water with foam that the paddlers dip in and out of, sometimes completely submerged before being spit out by the current.

Facing a force that has carved through rock for millions of years comes with risks. Last year’s Great Falls Race was canceled after the death of 23-year-old Shannon Christy during a practice run. It was the third death of a kayaker on the Falls since McEwan’s first run and a jolt to the tight-knit community. Many of the area’s top racers were instrumental in the three-hour recovery effort to retrieve her body.

Being overly prepared is a crucial practice, Landon sophomore Robert Waldron said.

“When we are out running the Falls, a lot of people think we’re crazy guys or daredevils,” he said. “ It’s not really clear that we’re not taking any more risks — we’re so prepared, we’re just doing what we know how to do.”

Waldron started paddling at age 9. He’s spending his summer vacation training twice a day in a sport that is, for him, “pure adrenaline.”

McEwan teaches that resilience is the most important thing you need as a paddler, whether someone is taking on the Falls or getting in a boat for the first time. Even the most seasoned kayakers are subject to the whims of the whitewater, and McEwan, by far the oldest paddler running the falls, was hospitalized last month after hitting his head while running a section of the river named “Fishladder.”

“You are going to make mistakes, but you cannot quit. Whatever you get, you get,” he said. “Your best safety is your own skill, and no one can rescue you like you can rescue yourself.”