The Grand Canyon encompasses 1.2 million acres, yet visitors tread on less than 5 percent of it, which suits Walters just fine.

"For the first mile, we'll see lots of people, but then they'll disappear," says Walters, beaming, on our first day. "By the second day, we won't see anybody."

With education in mind, we spend our first day on the rim in a GCFI classroom. Five of us have signed on for a three-day backpacking trip to Horseshoe Mesa, a remote promontory in the heart of the canyon, accessed via the Grandview Trail, which begins finely at the rim with a well-maintained series of switchbacks, then deteriorates from there. Janet, Ed, Chuck, Sean, and I range in experience (little to plenty) and age (33 to 67), but we share some common interests.

"I'm here for the adventure of backpacking the Grand Canyon," says Janet. "Ummm, people hardly ever fall, right?"

In the classroom, we review the importance of leave-no-trace backpacking. We discuss proper footwear and pass around one of Walters' socks, each student examining it as if it were a rune. We review compass and map-reading skills, as well as the contents of Walters' backpack. The man travels lighter than Peter Pan.

"Most people pack out of fear, not need," he says. "Ounces turn into pounds and pounds turn into pain."