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San Bruno, California, United States

Bay Area Ridge Trail: Fifield-Cahill Ridge Trail

A permit only section of the Bay Area Ridge Trail

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Difficulty: Moderate
Length: 13.2 miles / 21 km
Duration: Full day
Overview: This guide covers a 13 mile section of the Bay Area Ridge Trail.  It is a through hike that starts at the Sweeney Ridge Trailhead behind Skyline College and ends at Skyline Quarry near Hwy 92.  Elevation gained is about 2400' with 2800' lost.

The Fifield-Cahill Ridge trail traverses coastal scrub and old growth douglas fir forests.  The majority of the hike sports great views of the Pacific, SF Bay and the Coastal Range.  Wildlife spotting should be more favorable than other parks due to less human interference and the wildflowers are stunning in spring.

This trip takes some planning in that you need to select a date that is available, get your permits, and arrange for enough vehicles to shuttle your group North to Sweeney Ridge to start the hike.

Tips: Plan this hike well in advance so you can procure a permit for your group.
Dress in layers.  The ridges can be very windy and entrenched in fog while other sections have no shade and warm up quickly.
Pack a lunch for the the lunch break.
Bring plenty of water, there is none on the trail.
Toilets are located about every two miles.
Bring a camera for the views, wildflowers in the spring and the wildlife that isn't exposed to humans as much as in other parks.
Wear good shoes and socks with good padding.  It's a long hike on packed gravel roads.
Bring enough cars to shuttle everyone to Skyline College and at the end take everyone back up there to get the shuttle cars.  The docent will most likely ride with you.
Refer to your permit on where to meet and check the phone line a day or two before the hike for final instructions.

Available hike dates and permits are available here:

Points of Interest


Skyline College to Nike Missile Base

The hike starts at the back of Skyline college, this ridge is extremely windy and socked in with fog.  We had some great blasting winds that were giving the abundant crows some grief while they soared overhead.  Within a mile or so you reach the first building from the old Nike Missile Base in this area.  As your round the first building you make a steep descent and a steeper ascent up a staircase to get the missile base proper.  A group of delapidated buildings are on top of this ridge and worth sneaking away from the group for a couple of photies.

Bay Area Discovery Site

At this point you've gained a fair bit of elevation and now it's a nice walk along the ridge top with a stop at the Bay Area Discovery Site where Portola's Group discovered San Francisco Bay.  There's a neat Sighting Sculpture with most local peaks labeled and the Farrallone Islands. 

Entrance to SFPUC land

Around Mile 3 you enter the SFPUC land through a locked gate.  A SFPUC truck was waiting there when we arrived and seemed to shadow us for the entire hike.  Not sure if this was purely surveillance, boredom or compassion for people who may have trouble on this fairly long hike.

Lunch Break

We stopped for a lunch at Mile 5 or so at a nice spot with a new picnic table, a restroom(very nice and placed every two miles along this section) and a great row of trees to provide a windbreak.  Lunch was eaten quickly and we were back on the march.

Pilarcitos Lake and old growth Douglas Firs

After some number of miles the trail drops down into the Pilarcitos Reservoir area (you never really get a great view of it) and a fantastic old growth stand of Douglas Firs.  This section was amazing with ubiquitous Banana Slugs,  some great mushrooms and fungus to photograph and the truly amazing candelabra style firs.  I've read that some of these are 200-300 years old.  This was by far my favorite section of the hike.

Monterey Cypress and Quarry section

The hike ends with a descent through an eerie stand of Monterey Cypress that were planted here in the 1930s for reasons unknown. As you round the final corner you find yourself back in Skyline Quarry where you started. 
Pictures in this guide taken by: ruffwork, antonyw, stevelabo, Vaudesir

Bay Area Ridge Trail: Fifield-Cahill Ridge Trail Trail Map

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