Rock walls closing in, his kayak moving downstream fast, John Kiffmeyer approached the edge of Brownstone Falls. A final nudge and Kiffmeyer was airborne, his boat a missile flying four stories high inside a roar of white.

It was spring 2002, and Kiffmeyer, a machinist in his mid-20s from Big Lake, Minn., was attempting a risky waterfall drop on the Bad River in northern Wisconsin. The right line would net Kiffmeyer a bit of glory in the local creek-boating scene. A wrong move on Brownstone Falls, which jets 40 vertical feet in a tight gorge at Copper Falls State Park, would send Kiffmeyer to the hospital.

Creek boating -- a subset of whitewater kayaking in which paddlers seek narrow streams, fast currents and waterfall drops -- makes no pretense about risk. It is a sport that focuses on streams so steep that they look like water slides. Rapids tumble and explode, and expert-level Class V whitewater is the rule more often than the exception. Currents on some streams can pull a kayak completely under, its occupant suctioned along for the ride.

Started as a fringe movement

Nationwide, about 2.2 million people take part in whitewater kayaking, according to the Outdoor Industry Association of Boulder, Colo. Creek boaters are a small percentage of that figure.

The Sierra Nevada range in California, the Rocky Mountains and streams in the Southeast are creek-boating hot spots. But in the Upper Midwest, where rivers drain an immense watershed surrounding Lake Superior, dozens of creeks play host to kayakers in search of a rush.

"When the water is up, the Lake Superior area is as good as anything," said Peter Noren, a veteran kayaker from Minneapolis who manages the boating department at Midwest Mountaineering. "The density of streams is unique."

More than 25 navigable rivers and creeks lace Minnesota's North Shore alone, from Duluth's Amity Creek to the Pigeon River at the Canadian border. Two dozen more creeks and tributaries cut through Superior's South Shore in Wisconsin and Michigan's Upper Peninsula, making the Midwest a little-known mecca for steep-water seekers such as Kiffmeyer.

It's partly risk assessment

At Brownstone Falls in 2002, where the boaters got out to scout the 40-foot drop before pushing through, Kiffmeyer steered his kayak slightly off route. Missing the main pool at the base of the falls, his boat nosedived into solid stone just slightly submerged, breaking Kiffmeyer's ankles on impact.

"It felt like falling onto cement," said Kiffmeyer, now 33.

Despite the injuries, he remains an avid creeker, running dozens of streams most years from March until water levels subside.

Rare accidents aside, the sport is reasonably safe for boaters versed in scouting lines, reading the river, "boofing" drops and snagging eddies for a pause in the action.

Gear has evolved in the past decade. Like many creekers, Kiffmeyer wears a watertight dry suit to make boating bearable even when snow is still melting off the river banks. His boat is a high-volume torpedo, buoyant and almost unsinkable. A helmet, booties and elbow pads protect him from rocks encountered at high speed in the current of falling water.

On rivers such as the Lester in Duluth, a 2-mile flume through the east end of town, precise paddling sends kayakers off ledges and through long sluiceways, red rock walls towering above. Or try the Split Rock farther up the North Shore, where steep whitewater rolls over a half-dozen slides, including Class V descents.

Joining the action

Last month, after a spell of heavy rain, Kiffmeyer and five friends met in Duluth for some late-season creeking. I found the group on Hwy. 61 and made plans to hike and observe the boaters in action.

Tommy Norton of Minneapolis suggested a "hike and huck" session at Illgen Falls on the Baptism River.

"We carry the boats in and drop the falls," he said. "Quick in and out."

And so the crew shouldered their kayaks and tromped down a trail. In 10 minutes, Kiffmeyer, Norton and Joerg Steinbach of Mounds View were suited up and ready to fly.

Sitting in an eddy above Illgen, the roar of falling water canceling out conversation, Kiffmeyer signaled his intention to drop.

Water converged a few feet from the put-in, a foamy root beer shot from a jet. The curtain fell vertically for 30 feet, a wall of mist and white. A dozen quick paddle strokes and Kiffmeyer was part of the cascade, gravity grabbing a body in a craft, plummeting like a stone dropped into the deep.

Kiffmeyer held his paddle high, and his boat nosed Illgen's frothy pool. His shape sunk in, then bobbed back up, bow aimed downstream while Kiffmeyer raised an arm in victory.

Safe and unscathed, the boater spun on the water. He dipped a paddle in and pushed, nudging the boat away from a wall, turning to float toward the whitewater gorge rushing downstream, roaring beyond.

Stephen Regenold is a Twin Cities writer and author of the syndicated column www.thegearjunkie.com.