Canyon Overlook Trail starts near the east end of the Zion-Mount Carmel Tunnel and reaches one of the park's best short-hike viewpoints. The route is brief but not flat, with ledges, railings, alcoves, and slickrock before the canyon suddenly opens below.
Parking is the hard part. The small lots near the tunnel fill quickly, and traffic cannot simply stop wherever it likes. Go early, be patient, and do not make this the only plan of the day if parking is impossible.