On October 1, 2019, Nick Eastridge set off from Lees Ferry to walk through Grand Canyon National Park, paralleling the Colorado River on its north side below the rim along its 277 mile length inside the park. Because cliffs often prevent a direct path along the river, the actual walking length was over 600 miles, most of it bushwhacking and scrambling off trail. After 72 days spread over three trips, Nick reached the western end of the Grand Canyon on October 7, 2021. This book is the story of the hike.