Tonto Trail is the longest trail in Grand Canyon National Park, many hikers follow a part of it, but very few hikers follow it entirely. Unlike those trails from rim to river, it runs along the south bank of the Colorado River, mostly on the Tonto Platform. The Tonto Trail officially begins at Garnet Canyon and ends at Red Canyon.  If you have finished R2R2R, Tonto Trail might be your next challenge in the Grand Canyon.