Hike | Hidden Valley Trail | South Mountain



South Mountain is one of the most notable mountains in the East Valley due to its different trailheads in Ahwatukee, Chandler, and Phoenix. Taking the Mormon Trail and connecting to the National Trail can access one of the most scenic trails, the Hidden Valley Trail Loop. People may know the trail loop by its famous points of Fat Man’s Pass, and the lesser known but equally beautiful Hidden Valley Tunnel.


  • Length: 3.4 mi
  • Trail Type: Out and back
  • Elevation Gain/Loss: 918 ft.
  • Difficulty: Moderate
  • Kid Friendly: Yes!
  • Dog-Friendly: Yes, dog must be on a leash!


Starting at the Mormon Trailhead, the trail immediately starts to ascend up boulder-like terrain. The trail weaves up and around the side of the mountain with quick elevation gain and beautiful views of Phoenix. Throughout the trail, marked poles with the letter “M” lead the way so that you will not get lost. At the end of the Mormon Trail, connect with National Trail West for about 0.1 miles until it reaches the Hidden Valley Loop, which is denoted with a clear sign. Due to the direction of the sun, going the way to the Hidden Valley Tunnel is recommended so that you can return on the loop with the sun behind you. Keep your eyes on the rocks because petroglyphs from the Hohokam tribe can be seen!

Hidden Valley Tunnel is formed naturally from boulders and is the entryway to some of the most breathtaking scenery of the trail due to unique boulder piles. Although the trail has been well marked until the loop, here is when some parts become unclear. Following the trail, it will seem to end at a boulder wall corner. The correct way is to climb up those boulders to the rest of the trail. There will come another point soon after where the trail seems to end at a long wall of humongous rocks. Climb straight up and over these rocks as well.

Finally, you will end the loop at Fat Man’s Pass, which is a very narrow passageway formed by huge boulders. This is a popular rest and picture spot! Follow the loop back to the intersecting point with National and return home the way you came.

Remember: This trail is multi-purpose so be mindful of the mountain bikers!



To get to the Mormon Trailhead, take exit 155 for Baseline Rd. Turn left on Baseline, left again onto 24th st., and follow the curve through the neighborhood until you reach the parking lot at 8610 S. 24th St., Phoenix, AZ 85042.


1. Wear hiking boots or trail shoes if you have them due to the rocky and nature of the trail and loose gravel

2. Bring and drink enough water throughout the hike – 1-2 Liters will be adequate.

3. Wear sunscreen, a hat, and sunglasses to protect yourself from the sun. During the Summer, starting before 7AM is recommended to avoid the sweltering heat. There is not much shade along this trail.

4. Enjoy the trail! Watch your footing, but make sure to look up from time to time to drink in the panoramic city and boulder sceneries!

5. As always, pack in what you take out! Leave no trace.


This blog was thoughtfully written by Annie Nguyen. You can find her on Instagram at @_annien.

* Please remember to hike at your own risk. To learn more please refer to our Hiking Disclaimer