Scrub oak “tunnels” on the Camino Ruiz Trail.

This is the only trail that accesses Los Peñasquitos Canyon Preserve from the south rim between Black Mountain Road and the West End parking lot off Sorrento Valley Blvd. Before the Camino Ruiz Trailhead was established in 2009, it was difficult to access the canyon from the south side. The upper portion of the trail is steep with loose cobbles. It is shared with bicycles and poison oak is prevalent. Rattlesnakes are common, although the trails are wide enough that you can easily avoid them.

An acorn woodpecker atop his granary on an old sycamore stub.

This trail is unique in that it gives you a chance to hike under a canopy of scrub oaks that make you feel as though you are in a tunnel. The majority of the trail is in the shade, which means there is typically more moisture. While the Camino Ruiz Trail is only 0.6 mile long, once you reach the riparian zone at the bottom, near Los Peñasquitos Creek, you have numerous options for continuing your hike. If you go to the left when you get to the main south-side trail in the canyon, the waterfall on Los Peñasquitos Creek is about 1.9 miles further (round trip from the trailhead would be about 5 miles). If you go to the right, Los Peñasquitos Creek crossing is about a quarter of a mile ahead. There is also a single-track trail on the south side of the creek that is shared with horseback riders.

The waterfall is a delightful location to get your feet wet or have a picnic. There is water here year round. It is a little bit of a challenge to cross the creek here, but if you are surefooted, it is definitely a possibility.

As with most riparian zones, Los Peñasquitos Canyon is a place where wildlife is plentiful all year long. There are many acorn woodpeckers, red-shouldered hawks, and kites. It is not uncommon to see bobcats, coyotes, raccoon, rabbits, and mule deer. An early-morning or dusk hike yields the best opportunities for seeing or photographing the wildlife.

The trail is accessible year-round with late-summer blooms such as buckwheat and golden bush. The oaks are evergreen, providing shade all year. In the spring, you will see a profusion of mushrooms, lichens, mosses, and other species that like the dampness. The spring flower bloom is spectacular from March through June with blue-eyed grass, fuchsia-flowered gooseberry, wild onions, and milkmaids, along with many other typical chaparral plants.

• Distance from downtown San Diego: 20 miles. Allow 25 minutes driving time. (Mira Mesa) From CA-163 N, merge onto I-15, then Mira Mesa exit and go west to Camino Ruiz and take a right. Go to the north end of Camino Ruiz to find Camino Ruiz Community Park. The trailhead is on the left after the first few parking spaces.
• Hiking length: 5 miles out and back.
• Difficulty: Moderate hike with about 200-foot elevation loss/gain. Restrooms available at the park. The park gate is closed at night — usually open by 7 a.m. Note: Los Peñasquitos Canyon is closed during and for at least 24 hours after a significant rainfall.