The first time I explored Glen Park Canyon, I was completely amazed that such wilderness remains inside San Francisco city limits. It doesn't feel at all like you're in a large city. There is a nice nature trail that goes up the canyon alongside a small creek that flows only during rainy days. We love exploring here. The main downside for us are the many dogs off leash (although they're supposed to be on leash in the park).
The fact that I lived in SF for at least 8 years before I ever entered Glen Canyon still amazes me. After moving close by and getting a dog we started coming here on a daily basis. It is now one of my favorite places to come on a sunny morning. It is full of paths, rocks and little places to explore. There are often people walking their dogs and parents walking their kids to and from the preschool located in the park. It's possible in Glen Park to forget you are even in the city! It is such a wonderful spot!
Full disclosure: I went here before I had my son. However, I felt I must write on this location because it's the best little hidden spot in SF.
The entrance looks so much like a normal park with tennis courts but when you get inside there's picnic areas and a hiking path that's not difficult but beautiful and interesting. This is a nice little place to spend an afternoon.
Glen Canyon, in San Francisco's Glen Park neighborhood, is where I go with my partner and our 9-month-old when we need a quick hit of wilderness. Trails wind through eucalyptus, oak, and redwood trees, along grassy hillsides and a lush creek bed, and past rock formations. It's easy to forget you're in a city.
We like to start on the dirt road at the Elk Street entrance and make a loop through the canyon. The route takes us along a wide dirt road, over the creek in two places, and through dense trees. There are also trails heading up the hillsides to the jutting rocks--great picnic spots with bracing views of the canyon.
Trails branch off here and there to create loops through the park, so you can easily choose your route according to your children's stamina. Families with strollers might want to stick to the dirt road, or enter the park off Bosworth/O'Shaughnessy and stroll along the flatter, wider trails closer to the rec center buildings. This area also has a couple of picnic tables, and there's a tiny playground with sand and low-tech toys to share. Our little one enjoys the baby swings.
Off-leash dogs have the run of the park (albeit illegally), so be forewarned if your kids aren't comfortable with them. (We've never had any trouble in the canyon with our own dog or anyone else's.)
Glen Canyon is a lovely walking, hiking, and picnicking spot pretty much all year round (except for rainy days, when many trails dissolve into mud). The deeper trails are downright magical on foggy days, and older kids would probably love picking the wild blackberries in summer. Enjoy!