Exploring Peña Adobe Regional Park in Vacaville, CA Peña Adobe Regional Park is a hidden gem located in Vacaville, California. This beautiful park offers a variety of outdoor activities, including hiking, picnicking, and exploring historical sites. Whether you’re a nature lover or history enthusiast, Peña Adobe Regional Park has something for everyone. In this article, we will take a closer look at the park, its amenities, and how you can make the most out of your visit.