SOMEWHERE BETWEEN PUTTING IN on the Colorado River at Lee's Ferry and emerging from the Grand Canyon at Diamond Creek Road, something will have changed inside you. While 4.5 million people each year come to gaze at the most epic piece of geography in the United States, only a lucky few see it from the inner gorge, paddling the full 226 miles through the red-rock chasm. Raft trips are terrific, but for a once-in-a-lifetime accomplishment, run the GC in a kayak. You'll churn through legendary whitewater like Class IV–V Lava, Crystal, and Granite rapids, earning every paddle stroke of the way.

Do the Grand Canyon right by planning the longest possible trip you can—two weeks or more (commercial trips range from six to 21 days). You'll want to really get the most out of the experience by sinking into the landscape and soaking up the river. Second, be ready for the white-water, lest you spend those 14 days scared and exhausted. Every day you'll be arriving at a new horizon line with pounding whitewater lurking below—Class IV washing machines like Hance, Horn, and Upset. But hone your kayaking skills beforehand and you'll be in good shape to master the rapids, not just survive them.

Go for It

Every September, Otter Bar Lodge Kayak School offers a 15-day guided trip through the Grand Canyon for skilled Class III+ kayakers, complete with motorized raft support. Guests must provide their own kayaking equipment. $3,100; 530-462-4772, www.otterbar.com

SKILLS & TIPS: You want to be a solid Class III whitewater kayaker with some experience in Class IV. Beware: The high-volume Colorado in the Grand Canyon can flip you over at any time. You'll need to be comfortable upside down in your boat, because you're going to be spending a lot of time that way. To develop a feel for GC-size rapids, get experience on quality Class III–IV runs like those on Wyoming's Snake, the Lochsa or the South Fork of the Payette, in Idaho, or Montana's Kootenai or Alberton Gorge in the spring, when the rivers are thumping. If you live in the East, Ontario's Class III–IV Ottawa River has big water all season long.

TRAINING: Kayaking involves short bursts of high-intensity output accumulating over the course of the entire day. Circuit training, with its functional, full-range movements completed at high intensity, is the best solution to get you in shape. Two or three times a week, follow 20 minutes of running or biking with any three of the four exercises below. Do a set of 5 to 15 reps of one exercise each minute, on the minute, for 30 minutes (for example, 15 overhead squats in minute one, ten dips in minute two, and five pull-ups in minute three; repeat). As your strength grows, increase the difficulty and number of reps of each exercise.

1) OVERHEAD SQUATS: Hold an unweighted barbell overhead with arms slightly bent. Stand with your feet shoulder width apart and squat down until your thighs are parallel to the ground. For more difficulty, add weights to the barbell; for less, hold a broomstick overhead.

2) DIPS: Lower yourself between a pair of dip bars while squeezing your elbows toward each other. When your arms are bent 90 degrees, press yourself back up until they're straight. Keep your knees bent to engage your core. To make it easier, put your feet on an exercise ball behind you; for a harder lift, hang weights off a weight belt wrapped around your waist.

3) PULL-UPS WITH BENT KNEES: Hang from a pull-up bar and pull your knees toward your chest, then start doing pull-ups while holding your legs in place. When you tire later in the circuit, hold yourself for 15 seconds in a bent-arm hang with knees drawn up. Advanced option: L pull-ups, done with your legs held straight out and rigid in front of your body.

4) ELEVATED PUSH-UPS: Assume a standard push-up position, with your legs elevated on a bench, chair, or large stability ball at a level higher than your head. Holding your torso straight, lower yourself until your elbows are bent 90 degrees, then push yourself back up. Later in the circuit, substitute normal push-ups (feet on the ground).
—As told to Frederick Reimers