The Grand Canyon, a barren labyrinth of light and shadows, was one of the last places in the American West to be surveyed. John Wesley Powell, before he made the first descent via the Colorado River in 1869, called it “The Great Unknown." Much of it still is today, and river runners, backpackers, lithic hunters and butte baggers seek prestigious “firsts” in the Grand Canyon’s innumerable technical slots. These canyons within canyons with their remarkable features that no human has seen before are what beckons Rich Rudow, Todd Martin, Dave Nally and a passel of other canyoneers to explore deep drainages. It’s no easy task, demanding knowledge of route finding, backpacking, climbing, technical rope work and pack rafting — so much so that Rudow was nominated for Outside magazine’s 2012 Adventurer of the Year.