The Zion-Mount Carmel Highway is the 23-mile section of Utah State Route 9 between Zion Canyon and US Highway 89. The western 10 miles of this route is in Zion National Park and park passes or entrance fees are required ($30/car, valid for 7 days). Note that the Zion Shuttle does not access this area of the park. The scenery along this route is unique and extraordinarily beautiful. Allow about an hour to drive it (20-45 mph), longer if you want to stop for lots of photos or hiking. We drove it westbound just after sunrise on a Monday morning in mid-September and traffic was light. Once inside the eastern park boundary, the paved, two-lane road twists and turns through a series of colorful, textured sandstone mesas and canyons and passes through two tunnels. The eastern tunnel is only about 500', but the western tunnel is 1.1 miles long. Vehicles like RVs that are 11'4" high by 7'10" wide or larger need a permit to pass through the tunnel, because rangers have to stop on-coming traffic so the oversize vehicle can drive down the center of the tunnel. The traffic control is only available during daylight hours and the hours vary with the seasons (see park service website and separate reviews about Zion-Mt. Carmel Tunnel). Due to the traffic control, drivers traveling this route may experience delays. West-bound drivers emerge from the tunnel to a jaw-dropping view of Zion Canyon. The road then switch-backs several times with 5-6 hairpin turns down the side of the mountain to the floor of the canyon and the junction with Zion Canyon Scenic Drive (see separate reviews, shuttle access only February-November). There are some places to pull over and take photos, but they are small and infrequent. I was frustrated by having to take photos through the windshield and out the car window. Lighting may be best for photos mid-day when the sun is overhead; in the early morning there was a lot of shade cast by the canyon walls. There are two trail heads: one at the eastern park entrance for the East Rim Trail (10.8 miles to Weeping Rock in Zion Canyon, may need permit) and one at the eastern end of the long tunnel for the Canyon Overlook Trail (1.1 miles). There is a small parking area for Canyon Overlook but when we visited it appeared to only be open to east-bound vehicles because the left-turn area from the west-bound lane was blocked by traffic cones. Neither of these trails are wheelchair-accessible. Restrooms are available at the eastern park entrance and the Canyon Overlook trail head.