Bull Valley Gorge is a 7.5 mile out and back trail located near Cannondale, UT and is rated as difficult. The trail is primarily used for hiking and is accessible from March until October.
I recommend to all that hike this trail - turn around after the narrows & go back the way you came. This is not an easy to find loop. We got lost & spent the night in the gorge. We hiked sun up to sun down 2 days in a row & got very lucky on day 2. We came out at Willis Creek at 9pm & walked another hour & a half to our vehicle. There was a Deputy at my Jeep. He told us about 4 to six people get lost every month & they usually airlift them out.
I'm fairly new to hiking slots but after completing a few in now in Southern Utah I have to say that this is my favorite so far. From the parking area hike on the right side of the canyon (sign in to the log book) for about 1 mile until the floor of the slots rise and you can easily climb or step down into the slot. Then start hiking back up toward the bridge. Going into the canyon too soon means you'll miss a good section of the slots.
There were very few obstacles during our hike (April 2015) and the few boulders blocking the passages were easily overcome. No ropes needed but the canyon is constantly changing so be prepared. We hiked about 2 miles through the canon before it started to snow on us so we turned around and retraced our steps...which were just as spectacular a second time.
Highly recommend this slot!