Box canyons are not, strictly speaking, canyons shaped like boxes; they are three-sided instead, an open box as it were, with steep, vertical walls of hard rock and lacking the ﬂoodplains of gentler and more traditional canyons. They can also be two-sided. As a 1900 brochure about Arizona’s Grand Canyon describes, “You are hedged in by dark walls on the sides, with a reddish-yellow strip of river below and a corresponding blue strip of sky above. You are in a box—a box canyon.” The walls of such canyons are unclimbable, and the lone exit route is often only the path of the river’s downstream ﬂow. Still, hikers and climbers often seek out such well-known examples as Idaho’s Box Canyon State Park, the Box Canyon Park near Ouray, Colorado, and Box Canyon near Wickenburg, Arizona.