"Many people rate Buckskin Gulch as their all-time favorite hike. The route goes through a beautiful slot that runs continuously for about 15 miles. (It may very well be the longest slot canyon in the world). It is deep, dark and narrow, with plenty of obstacles to make it fun. It is not a technical hike, but is rated as strenuous because of its length. You do have to scramble over rocks and wade/swim potholes.
Buckskin Gulch is located along the Utah/Arizona border, near Kanab. It can be done as a long day hike, if you are in good shape, but is best as an overnight backpack. The recommended route requires a shuttle. It is also possible to day hike from either trailhead, returning the way you went in.
Permit are needed to day hike and to backpack in this area, which is part of the Paria Canyon/Vermilion Cliffs Wilderness."