Tolay Lake Regional Park is located about 8 miles southeast of downtown Petaluma, bordered by hills between the Petaluma River and Sonoma.

The park is now open daily, after having been open weekends only while the park  master plan was developed. Visitor permits are no longer required.

At 3,400 acres, Tolay Lake is the largest of Sonoma County's regional parks. It is named for the seasonal lake that forms in the valley between its hillsides. The park includes Tolay Creek, extensive grasslands, and open ridges with views of San Pablo Bay, the San Francisco skyline and Bay Area peaks. 

The park offers trails for hiking, mountain biking and horseback riding.