The only exception was a rumpled-looking character whose shambolic disarray suggested that he may have been vacationing in the nearby bushes. His face bristled with several days’ worth of stubble. His hair jutted up daringly toward all four points of the compass, and his eyes bore a look of bleary insouciance that may have had something to do with the can of Budweiser clutched in his fist. But the most notable thing about him was that in addition to a torn T-shirt and a loose-fitting pair of Chaco sandals, he was sporting a pair of brown short pants that featured a conspicuously broken zipper in the crotch. It seemed clear that he should be given a wide berth. Until, that is, Rich mentioned his name, and I realized that this was someone I’d been hoping to meet. Andrew Holycross was a professor of zoology affiliated with Arizona State University who was widely regarded as one of the most respected herpetologists in the Southwest. An authority on all manner of desert reptiles and amphibians, he had a particular fondness for snakes, especially rattlers: Ridge-Nosed, Speckled, Banded-Rock, Western, and Great Basin, as well as the Mojave “Green,” the Arizona Black, and, of course, the Grand Canyon Pink, which is found nowhere else except where we were about to go….

As impressive as all this was, Holycross had somehow found the time in the midst of that work to hike the length of the entire canyon—not once, but twice. His first effort, a sectional transect on the south side of the Colorado in 2012, had been followed by a nonstop push along the north side in 2013. That back-to-back triumph, which had been pulled off by only two others, gave Holycross a better understanding than most people of the challenge on which Rich, a close friend, was now about to embark.

— A Walk in the Park: The True Story of a Spectacular Misadventure in the Grand Canyon by Kevin Fedarko