Lucas Valley Open Space in Nicasio, Marin County, offers real variety for hiking with your dog. The Big Rock Trail starts at the iconic Big Rock landmark and winds up to Big Rock Ridge Fire Road with solid views of the surrounding landscape. Dogs can stay on leash throughout the trails, or if your dog has reliable voice control, you can let them off-leash on the fire protection roads.

The Big Rock Ridge summit sits at 1,895 feet—the second highest point in Marin County, just below Mount Tamalpais. The panoramic views from up there make for genuinely nice hiking and a good spot to stop and catch your breath. From the summit, you can connect with the Loma Alta Trail, which ascends the southern half of the valley and gives you more vistas as you move through the preserve.

If you want something less steep, the newer trail offers a gentler grade than the Luiz Fire Road, which cuts a more rugged path through the area. The whole system is well-maintained, so it works whether you’re new to hiking or more experienced. The Big Rock Ridge Fire Road section is wide enough that you won’t feel cramped even with a larger dog.

Timing matters here. Spring brings the best conditions—wildflowers and green hillsides, without the mud that winter rains leave behind or the serious heat exposure of summer when shade is sparse. There’s no water along the route, so bring what you need. Winter can turn things muddy depending on recent rainfall, so check conditions if you’re going then.

There’s no entrance fee, and roadside parking is available. Since trails can vary seasonally and rules sometimes shift, it’s worth calling ahead to confirm the current pet policies before you head out. Bring water and snacks, and you’ve got a solid day ahead in the hills.