Supai Tunnel Rest Area Arriving at the Supai Tunnel rest area. There is a modern 3-spot composting toilet here, as well as a fountain with potable water (when in-season). This is also where mule rides from the north rim turn around.
This image is from the presentation "Desert Southwest - The Checklist Edition - Grand Canyon Rim-to-Rim Traverse, Day 3 - Cottonwood Campsite to North Kaibab TH".