24-mile long drive, which passes through the mile-long Zion-Mount Carmel Tunnel and winds down six steep switchbacks on its way to the canyons and high plateaus east of Zion Canyon. Vehicles over 7 feet 10 inches wide or 11 feet 4 inches tall must pay a $10 fee for using the tunnel since traffic must be stopped in order for the vehicle to drive down the center of the tunnel.