AS THE COLORADO RIVER muscles down the canyon, it stair-steps through more than 160 rapids, the largest of which can casually flip a 37-foot motor raft or smash a dory to pieces. Take Horn Creek, which is on our dance card this afternoon. It features a pair of exposed guard rocks upstream of a double hole backed by two hydraulic jumps that are sometimes called the Great Wave and the Green Guillotine.

The key to unlocking Horn Creek lies just below the right guard rock, where the current forms a shallow wave, known as a "lateral," that radiates downriver in an expanding triangle. A textbook entry starts on the far right side of the river and involves rowing—sideways and backwards—to a point just below the right guard rock. The trick is to build enough momentum so that you punch neatly through the lateral and into the calmer water inside the triangle. It's a straightforward move, but a heavily laden poop boat tends to complicate things. Imagine trying to row an outhouse, in reverse, down a wall of whitewater, and you've got some idea of what it feels like to take the Jackass through Horn Creek.

I watch as all four dories and Monte's Mule thread the entrance flawlessly. As several passengers raise their arms and yell "Whoo-hoo!" each boat skates across the tongue, harpoons through the lateral, and bobs merrily into the tail waves. Then it's my turn.

Among apprentice boatmen, mistakes are inevitable, and as I plow across the tongue I commit a humdinger. Instead of spearing cleanly through the lateral, I rebound off it and ricochet directly into the vortex. The top of the Great Wave surges over the front of the Jackass, hitting me in the face and chest with enough force to knock the lenses out of my glasses, drive me out of my sandals, and hurl me over the side of the boat, straight into the Green Guillotine.

Oh, hell.

The ordeal of being tossed into the center of a Class V rapid is referred to as "getting Maytagged." The wash cycle starts with a sharp crack to the side of my head—the blade of my right oar—as the current sucks me toward the bottom of the river.

In situations like this, veteran boatmen will tell you it's essential to remain calm. I'm in no mood to comply with this formula, however,
because even though I can't see a damn thing underwater, I'm pretty sure I know exactly what's happening to the Jackass up on the surface. In my mind's eye, it goes like this:

As the Great Wave flips the half-ton raft upside down, the boat drifts helplessly into the maw of the Green Guillotine, which starts clawing her to pieces like a pack of ravenous hyenas disemboweling the carcass of a wildebeest. As the lashings on the aluminum frame and the nose cones give way, my toilet supplies explode in all directions. But that pales in comparison with what I'm sure is being done to my poo cans. Unable to withstand the hammering, the lids are popping off, the rocket boxes are sinking like stones, and the collective contents of all five groovers are spewing out in a giant, thundering geyser: a toxic, 250-pound plume of raw waste that will turn this stretch of the Colorado into a Superfund site. It's an appalling debacle, and surely it will spell the end of my dream of becoming a river guide ...

Given what I'm picturing, it's actually a bit of a disappointment when Horn Creek's hydraulics, instead of drowning my sorry ass, shoot me toward the surface, where I'm squirted through the tail waves looking like a wet cat. I'm so horrified by what's happened that my best option seems to be to dive back underwater and stay there. But suddenly I see the transom of the Vale of Rhonda, with Miss Billie Prosser at the oars, ordering me to grab her gunwale.

"Oh, my God, Billie, the Jackass!" I sputter as I latch on to the side of her dory and get dragged through the water.

"No worries," she says. "The Jackass had a great run. Much better than you did."

And, sure enough, there she is. Despite my incompetence, my humble yellow dung barge has performed a series of deft solo moves—threading Horn Creek's maelstrom on nothing more than the shining fortitude of her own righteousness—and now she's bobbing in an eddy on the far side of the river. Beautifully upright, perfectly intact, she offers an important nuance to Steve Carothers's Philosophy of Poop:

Despite your best efforts, it is not always possible to deal with your shit responsibly. But every now and then? Your shit will just take care of itself.