Mormon Trail to Hidden Valley is a fun hike that features great views, petroglyphs, a natural tunnel and a tight squeeze through Fat Man's Pass. Fat Man's pass is a short, but narrow passage between two very large boulders.
The hike begins at the Mormon Trail parking lot in south Phoenix. The first mile of the trail is steep, with the most elevation gain happening in this portion of the trail. After ascending a little over a mile, you will come to the first fork in the trail. Keep to the right on Mormon Trail; the fork to the left goes to the Mormon Loop Trail. You will continue straight on this trail for about a quarter-mile before coming to the second fork in the trail. This is where the Mormon Trail ends and the National Trail and the loop to Hidden Valley begins. The National Trail is popular for mountain bikers, so be sure to use caution and stay alert on this portion of the trail. The loop is about a mile in length, and you have a choice to go to the left or the right at this point. The route to the left is recommended because it goes through the tunnel and lower part of the canyon first. It ends with a higher elevation and beautiful views on the descent.
After heading to the left on the National Trail you will continue for a short distance before coming to another fork in the trail. This is where you want to turn right and follow the sign to Hidden Valley. The natural tunnel is a short distance from this junction. The tunnel walls are smooth from erosion and provide a nice shady place to rest. After hiking through the tunnel, the trail follows a sandy wash. You will see a small trail that veers to the right between a large crack in the rocks. If you go between the crack, it is much easier than following the wash, which will lead you to a dry waterfall that is much more difficult to climb. At the top of the dry waterfall you can find a small panel of petroglyphs on the left side of the canyon. From here, continue to follow the trail for about another half-mile before reaching Fat Man's Pass. Fat Man's Pass is a very narrow passage and can be difficult for some people to get through. You can climb around the passage if needed. Immediately after going through Fat Man's Pass you will come to a fourth fork in the trail. Be sure to keep to the right and follow the trail up the hill. From here, continue the loop on the National Trail until reaching the junction with Mormon Trail to make your descent.