A grassy island rising above the sea of development on the northern San Francisco Peninsula, San Bruno Mountain offers striking views of the urbanized region.
The mountain features a two-and-a-half mile long trail that runs along the ridgetop. There’s a parking lot at one end so if you just want to see the best scenery, you can drive up there and hike out and back along the ridge. A loop hike would be more enjoyable, but there aren’t any official options, so for this hike we close the loop by using an unofficial trail that descends steeply from the ridge to downtown Brisbane.
There are, in fact, three unofficial trails from the ridge to Brisbane. The first is a very steep dirt road covered with a deep layer of 1–2 inch gravel that makes footing extremely difficult. Next is an unofficial trail that switchbacks downhill through dense woods; the grade is reasonable but it’s long, narrow, and overgrown. Finally, right at the end of the ridge road, is a singletrack trail that drops straight downhill; it’s steep but at least it’s well-worn and short. For this hike we use the third option, which shouldn’t be attempted if the trail is wet.
The hike is easier in the clockwise direction, since you get all the climbing over at the beginning and it’s a lot easier to climb the unofficial trail than it is to descend. But I’ll describe it in the counter-clockwise direction because that way the scenery gradually improves throughout the hike, and also, at the moment some of the trails are one way in this direction.
Here’s the trailhead location in Google Maps.
Park in downtown Brisbane, on San Francisco Avenue next to Brisbane Community Park. Walk down San Francisco Avenue to Quarry Road Park and take the wide paved trail. Take the first trail on your right, a narrow paved walkway that descends to South Hill Drive. Cross the road and continue straight ahead on the Crocker Park Recreational Trail.
The Crocker Park Recreational Trail is a dirt road that loops around an industrial area. It appears to be an old railway route. After 0.85 miles, turn left onto West Hill Drive, which is the first paved road crossing; then turn right onto Silverspot Drive. Walk up the left side of the road and take the paved path that climbs between some houses. Turn left at the second paved road and continue to the cul-de-sac, where there’s an unmarked and unmaintained but apparently official trail that climbs (through a little poison oak) to a water tower.
Take the Old Ranch Road Trail, which it climbs through eucalyptus groves and chaparral; you’re rewarded with the first views of the hike, over Brisbane.
The trail leads to the Radio Road parking lot. Continue through the lot and take the Summit Loop Trail, which descends through chaparral before beginning a gradual climb, eventually offering views over Daly City. Up to now the hike has been a little dull, but as the trail clmbs the scenery gets progressively better. This is also the busiest part of the hike, with a group every 5–10 minutes at peak times.
Continue on Radio Road or the Ridge Trail to reach the ridgetop dirt road. The road meanders along the ridge with a lot of ups and downs. This is the real payoff of the hike, with increasingly spectacular views of San Francisco to the left and South San Francisco and San Francisco International Airport to the right.
At the 2.5 mile marker, look for a well-used trail that breaks off to the left. If you come to a chain link fence, you’ve gone a little too far.
The trail descends at an unpleasantly steep gradient. As long as the trail is dry it’s barely manageable, but even so people often slip on the gravel. After about a quarter mile the trail levels out; although it’s not marked, this lower, level section might actually be an official trail. Turn left when you reach someone’s driveway. The trail emerges at Firth Canyon Park.
Take Glen Park Way, which descends through suburban Brisbane, and return on San Bruno Avenue.
© 2020 David Baselt