In British Columbia, we mostly hike ridges to high points,   In Utah, many hikes are through canyons, especially on the Colorado Plateau.   In Zion National Park, there are hundreds of canyons to explore and a few of them having regular hiking trails in them.   One of the more unusual ones is Hidden Canyon.

The trailhead and the first kilometre follows the Observation Point Trail (link).  

At this point a sign points the way and another warns the hiker of potential dangers.

After a short climb, the "shape" of the trail becomes apparent.   It is a ledge cut out from the sheer red sandstone face, contouring around to the mouth of a hanging valley.   In some spots there are chains to assist hikers and in other spots, we just hugged the wall   At some of the most exposed spots, the ledge-trail is only 4 feet wide.

Hidden Valley is a slot canyon that ends at a sheer dropoff into Zion Canyon.   Once we traversed (carefully) over into the canyon, we followed the sandy floor up the canyon to a natural arch.   Past the arch, another sign declared this was the end of the official trail and beyond was unmaintained and probably unsafe.  We continued on as far as we could, preferring to turn around when we were ready to do son, encountering new challenges every hundred metres or so.   Most were scrambles up rock barriers.   The last ones we tried had some exposure, manageable in dry condtions, but slow and careful work.  The upper canyon opened up under the towering cliffs of Cable Mountain and the Great White Throne.   We returned by the same route, still amazed by the trail on the ledges.   If you go to Zion, this is a must do hike, but be prepared for the exposure on the cliffs over to the canyon.