EASTERN ONTARIO IS SILO COUNTRY, a canvas of flat farmland, shambly barns, and hoof-stamped fields stretching in all directions. Except for a few gradual rises and dips, there's nothing to suggest that one of Canada's largest rivers roars through this blank landscape, nor that this river—in springtime, the color of root beer shaken to a froth—funnels off a steep ledge and boils into one of the largest standing waves in the world, a feature both feared and revered by the world's best whitewater kayakers. On a too-cold Tuesday evening in early May, less than a week after the Ottawa River surrendered its last ice floes, 175 of these kayakers have come to battle the monster wave known as the Greyhound Buseater in the 2007 World Freestyle Kayak Championships.

By far the most famous on the roster is Eric "E.J." Jackson, the big daddy of freestyle and—by his own estimation and nearly everyone else's—the most decorated paddler in history. The three-time world champion is father and coach to two enormously talented pro kayakers as well as president of Jackson Kayak, the country's fastest-growing whitewater-boat manufacturer. At 43, he's the patriarch of his own paddling dynasty, with an XXL personality and, some say, an ego to match. He's here with his wife, Kristine, 37, and their superstar spawn, 17-year-old Emily and 13-year-old Dane, to attempt the first-ever Jackson world-championships sweep—or, in less modest terms, total global domination of freestyle kayaking.

The odds are stacked in their favor, and the mood is optimistic—if chaotic—at Jackson HQ on the eve of the competition. The family has taken up residence in a rented clapboard farmhouse, half a mile from Buseater. Their giant white RV, with JACKSON KAYAK emblazoned across it, is parked in the driveway, and boats of every color are scattered across the lawn. E.J., Dane, Emily, and Emily's boyfriend, 18-year-old Jackson-sponsored paddler Nick Troutman, are just back from their final practice session and are slinging drytops and soggy spray skirts over the front-porch railing.

"Buseater's in, and it's huge!" E.J. cries excitedly, his bristly black hair still wet from the river. Compact and muscular at five foot six, he buzzes around in a blur of nerves and boyish, unfiltered enthusiasm.

Inside, a dozen Jackson-sponsored paddlers—some here to compete, others simply to support the tribe—are huddled around laptops, editing the company's new promotional DVD. Kristine has left for an event organizers' meeting, so dinner is self-serve and not your standard high-performance fare: potato salad, Lay's straight from the bag, plain Wonder Bread buns, root beer, and a bowl of grapefruit.

E.J. skips dinner and holes up in the RV to plot his freestyle routine on a computer spreadsheet. In tomorrow's preliminary round, he'll have four 45-second rides on Buseater to churn out as many acrobatic moves as possible, some of which—like the McNasty, a twisting aerial somersault—he's minted during his 15-year freestyle career. Each trick earns points for execution and difficulty, and E.J.'s program helps him calculate which combination of moves will generate the highest score possible.

"I do get nervous in the early rounds," E.J. admits when he emerges an hour later. "You don't have to go all out; you just have to stay in the game. I do best under pressure, when it's win or lose."

To psych himself up, he finds a seat at the dining-room table with the others to watch the promo video. "Check that out!" E.J. cackles as his onscreen self does a backflip on Uganda's White Nile, where he and the Jackson pack trained for five weeks last winter. "Sweeeeet!" Dane, who's been lounging on a trundle bed in the living room playing Xbox, hops over in his sleeping bag to watch.

Later, after E.J.'s gone to bed in the RV, the non-Jacksons sit around the kitchen table discussing their boss's prospects for the competition. "His practice runs today were disastrous," whispers Clay Wright, 40, a pro boater and Jackson Kayak field marketer, arching his eyebrows for effect. "He looked foreign to me out there."

It's not a good sign, given the herd of hungry young paddlers who want nothing more than to take down the defending champ and crush his legendary bravado. But for E.J., there's more than another victory at stake. He's built a business—and a family life—around his paddling prowess. Another win at the worlds will boost his cachet, which is good for his company—four years old and on the verge of profitability—and, in turn, good for his wife and kids. It's a precarious arrangement, but E.J. is unfailingly upbeat.

"I absolutely want to win, because all the indicators are that I should win," he tells me at one point. "Nick will do wonderful. Second place will be fine for him."