FINALS DAY ON THE OTTAWA IS BRIGHT and cloudless, the DJ's hip-hop is deafening, and the Ottawa is raging with such ferocity it's as though someone is blasting the Arctic ice cap with a blowtorch. To create Buseater, the river slides down an embankment and whips itself into a ten-foot-tall standing wall of whitewater known as the "pile"; beneath that is the "pit," where the competitors launch their flips, spins, and aerials and try not to get sucked into the wave's watery jaws.

Over the past two days, E.J. squeaked through preliminaries in fourth place and made it through the quarterfinals looking tentative and grabby, as though the fate of the Jackson dynasty hung on his every paddle stroke. But judging by the reaction of the rangy teenage shuttle driver who picks me up at the Jacksons' farmhouse, maybe it doesn't. "The E.J.?" he says, visibly wowed. "People are horny for his boats!"

On the river, there's no shortage of speculation and smack talk about E.J., the usual mix of eye-rolling and begrudging awe. I catch up with Jackson Kayak pro Billy Harris, 33, who's just been eliminated by his boss in the semifinals. "If we're playing volleyball, where do you think Eric's gonna put the ball?" he asks, laughing. "One hundred times out of a hundred, he'll spike it to the weakest player. And what if it's his daughter? He'll smoke it into her every time!"

Rush Sturges, 22, a big-wave paddler who missed the cut in the quarterfinals, puts it more bluntly: "E.J. is a machine. He's full-on out to win this event."

Most people are betting on Troutman, but the Jacksons seem focused, not worried, and as the day goes on they just seem psyched. E.J. plays pumped-up stage parent, parading around in an ankle-length fleece muumuu and flashing Emily a peace sign after she wins the junior women's division. When Dane, looking tiny but in charge on Buseater's back, takes third among junior men, Kristine picks him up and hugs him, his feet dangling in the air. If he's disappointed, he has five minutes to show it.

At 4 p.m. it's time for the men's finals. The five remaining kayakers—including Troutman and E.J., who's the oldest by 15 years—have three chances each to land their biggest moves; the paddler with the single highest-scoring ride wins. E.J., bobbing in the eddy in his canary-yellow Jackson All-Star, blows a kiss to Kristine, then grabs the tow rope, which is looped around a tree at the river's edge, and leans hard into the current. Skimming across the water, he beams up at the judge's booth and his family and several hundred spectators. Then he lets go, dropping off into the top of Buseater and into a smooth, high-speed sequence of back- and front flips, spinning blunts and Pan-Ams, and a McNasty. All of the attendant drama of the past few days and years—his close calls and flushes, diligent strategizing, and obsession with branding victory—dissipates as he makes every move.

After E.J. has won his fourth world title, surprising everyone and no one, and Nick has finished third in his first world championships, and E.J. has taken his victory lap on Buseater—surfing it without a paddle—and Kristine has allowed herself one small breath of relief, the Jacksons regroup at the farmhouse. I'm expecting a blowout party (that will come later), but for now it's family life as usual: folded laundry and video cameras on the dining-room table, footage to edit, and scores to report. Only E.J., sporting a skinny checkerboard tie, matching slip-on Vans, and a pleased, Peter Pan grin, looks truly relaxed. "I'm never nervous in the end," he tells me. "If I made it that far, it means I got to play the whole way."