Taking the Bright Angel trail from the south rim to the river, hikers walk 7 miles and descend nearly a mile. It can cool on the rim and get increasingly hotter as they get deeper into the canyon. Dehydration is a common problem for hikers. Two days are required for strong hikers to walk down and back up. Because of the extreme strenuous nature of the hike, some ride mules down to the river and Phantom Ranch. Either way, the path is breathtaking.