In an effort to share the uncharted glory and to shed light on the myriad threats faced by the crown jewel of America’s National Parks, writer Kevin Fedarko and photographer, filmmaker and Sony Artisan Pete McBride set off on an audacious and demanding adventure—to cut a transect, on foot, across the entire length of the Grand Canyon.

Estimated at more than 750 miles, the hike was brutal beyond their wildest expectations. McBride and Fedarko carried as much as 50 pounds of gear, equipment, and food strapped to their backs and had no trail to follow, risking severe consequences with a single misstep. But even as they pushed themselves to the brink of their physical and mental limits, the unrivaled beauty of the canyon and their motivation to protect it drove them onward. Hear their behind-the-scenes stories of this grueling but critical expedition, illustrated with stunning visuals.