"My interest in photography did not begin with a burning desire to see the world through a camera. It evolved through an intense devotion to wilderness that eventually shaped all parts of my life and brought them together." —Galen Rowell

This shooter's empathy, as it might be called, is a nearly universal trait among whitewater river photographers, the vast majority of whom first picked up cameras to document their own expeditions or their friends' crazy stunts. Some, like Charlie Munsey and Dunbar Hardy, are world-class kayakers--or at least were in their prime.

"My paddling ability is directly proportional to the type of photographs I'm able to shoot," says Hardy, 38, from Boulder, Colorado, who also organizes and guides international kayak trips. "When you actively participate in the sport, you can anticipate what the paddler is going to do. And you have to have technical paddling skills to even get into some of these places."

Munsey, 40, of White Salmon, Washington, also knows the feel of make-or-die maneuvers in big water. He did his postdoc studies on the North Fork of Idaho's Payette River, a 16-mile Class V cascade that gave him the skill and confidence to tackle merciless torrents worldwide--including the legendary Grand Canyon of the Stikine River in British Columbia, which he was the eighth paddler to conquer.

Munsey is happy to portage a man-eating chute these days--especially if he knows the hike will put him in position to document someone else running it. "I kayaked so much for a long time and pushed it and pushed it and scared myself a lot," Munsey says. "It got to the point where capturing those great waterfalls and rapids on film was more satisfying to me than a waterfall run that lasts a few seconds."

Munsey's decision to stay on the sidelines has served him well. In 2002 Outside magazine dispatched him to document the first descent of the Tsangpo River in Tibet--a two-month epic that ranks among the sport's great adventures. "When I saw the first rapid and what they were up against, I knew I'd made the right decision," he recalls, "because it was only going to get worse."

Through most of the Tsangpo journey, Munsey had ample time to hike ahead and set up photos while the paddlers scouted runs. But in some places he had to bushwhack 3,000 feet or more to the top of the gorge, then back down to the river--detours that took up to 12 hours through snowfields, mud slides, and bamboo forests--to circumvent sheer-wall stretches the kayakers stroked through in minutes.

Because there are no do-overs in the belly of a Himalayan chasm, shooting such an expedition calls for a documentarian's spontaneity and flex. Most whitewater money shots take hours of planning and repetition, thus violating the photojournalistic creed that rigid preconception begets bad art.

Like Munsey and Hardy, Oregon photographer Jock Bradley steadfastly adheres to the Ansel Adams-Galen Rowell principle of "previsualization." Even in such a high-risk, high-action genre, Bradley all but storyboards the images he hopes to create. Once, to snare an underwater shot of a kayaker penetrating a river after a drop from on high, he schlepped many pounds of scuba and camera gear through a mile of wilderness to a pool with an ideal mix of sunlight, clear water, and cliffs. "It was very much a set-up shot," says Bradley, 46. "I had three kayakers taking turns off this rock 12 to 15 feet high. I'd lie on the bottom with the scuba gear on, maybe six feet deep, and hold my breath until the bubbles dissipated. That would take about 45 seconds. As soon as the bubbles were gone, the kayaker would seal-launch off the rock, and I'd hit the motor drive. I burned through about ten rolls of film, close to 400 shots. Out of that I got one frame that captured what I was looking for."

That daunting fail rate is far from unusual. Blame the fickle lighting of canyons illuminated by thin and constantly moving slices of sun.

"It tricks your camera," Munsey says. "You have to just ignore your meter."

"Shadows go black and highlights go white," Bradley explains. "It's difficult."

The exposure complications are especially tough on photographers looking for that rare union of action and scenery, who want the ribboned granite in the background and the suicidal kayaker in the foreground to inspire viewers equally. These photos are the most difficult and gratifying to capture because they derive from an insider's POV--the shooter's attempt to duplicate images archived on his or her internal hard drive during a lifetime on the river.

"It might be something I saw once on a kayak, like a river rainbow--you turn a corner, and it takes your breath away," Munsey says. "That's the shot I'll go looking for. Out of the thousands of images I've taken, I have maybe five or ten where the stars have aligned. But I'm not disappointed when it doesn't happen, because most of the time it doesn't happen."

Steve Hawk is a writer, editor, and consultant for action-sports magazines and television and the author of Waves (Chronicle Books, 2005). His work has appeared in the Los Angeles Times, Outside, and Harper's.