Hidden Valley Hiking Trail – South Mountain
- Difficulty Level: Moderate
- Length: 3.5 Miles (roundtrip).
- Location: Mormon Trailhead (24th St. & Baseline)
- (From Baseline turn onto 24th St. towards the mountain and you’ll run into the parking lot)
This is definitely the Phoenix hiking trail that has the most unique rock structures. From a naturally formed tunnel, to boulders squeezed so close together, creating a small pathway (known as Fat Man’s Pass), Hidden Valley is a must do hike!

Getting onto Hidden Valley Hiking Trail
To get onto this trail you need to start at the Mormon Trailhead, on South Mountain which is located at 24th Street and Baseline.
Seeing as how Hidden Valley is located in the middle portion of South Mountain, you need to take Mormon Trail, to National Trail, which then will intersect with Hidden Valley. So really, Hidden Valley itself is a short mile hike at a half mile, however you need to take two other hiking trails to reach it, making the total distance 3.5 (roundtrip).
For this reason, the most direct route is to hike the switchbacks of Mormon Trail until you see the signs for National Trail. Mormon trail is just a little over a mile and is moderate to difficult. It begins on an incline which won’t let up until you are at the end of the trail.

At the end of Mormon trail, when it begins to flatten out you’ll notice trail marker indicating that you are now on National Trail. Follow National for about a half mile and you’ll see the sign for Hidden Valley.
Hidden Valley is a Loop Trail
Hidden Valley is a loop trail, that connects itself onto two different spots on National Trail. The first sign you come up to will be to enter Hidden Vallen via the Natural Tunnel. If you pass this sign and continue along National, you’ll see the second sign for Hidden Valley, via Fat Man’s Pass.
It’s up to you, which starting point you want to take. Just be sure to remember that once you have completed Hidden Valley, you need to turn right back onto National, to get back onto Mormon.
For this trail write up, we began at the second sign, via Fat Man’s Pass.
Fat Man’s Pass
Immediately, as you dip down into Hidden Valley, Fat Man’s Pass lies right there greeting hikers. As mentioned above, this unique rock formation is two huge boulders that are almost touching each other, causing a very narrow pathway.
If you’re small enough you may be able to squeeze through. Or if not, you will be able to walk on top one of the boulders and continue on the path below.


Once after Fat Man’s Pass you will continue walking along the path, entering into a wash section. As you continue, more boulders piled up upon each other will emerge from the side of the trail. It seems like a perfect hikers playground. Lot’s of rocks to climb and areas to explore while you continue walking along the path.


Hidden Valley’s Natural Tunnel
As you approach the end of Hidden Valley, one last final rock formation is waiting for you. Known as the Natural Tunnel, it is created by two boulders being close enough together to create a hallway to walk through…while another big boulder sits on top, creating a roof.



As you step back onto National Trail, turn right and go back down Mormon Trail, the way you came up.
Phoenix Hiking Trail Essentials:
Over 200 hikers a year have accidents along the Phoenix hiking trails. The desert is a beautiful wide open space but with that also comes a bit of danger that all hikers need to be aware of and be prepared for.
To give you the best hiking experience be sure to bring these following essentials with you on your Phoenix hike
- Water
- Sunscreen/Sun Protected Clothing
- Hat
- Sunglasses
- Salty Snacks (electrolytes)
- Durable shoes
Wind: 6mph W
Humidity: 15%
Pressure: 30.14"Hg
UV index: 1
75/50°F
77/46°F
72/46°F
66/43°F