Malibu Creek State Park is accessible in Calabasas, at 1925 Las Virgenes Road, south of Mulholland. The park has over 8,000 acres of rugged, beautiful hills, trails and scenery. The park stretches from Agoura Hills down to Malibu, down to Malibu Lagoon State Beach, covering much of the 25 mile Malibu Creek that flows from Boney Mountain down to the Lagoon. Malibu Creek is the only stream channel that crosses through the Santa Monica Mountain range.
There are three natural preserves in the park, Liberty Canyon, Udell Gorge and Kaslow, which protect Valley Oaks, rare plants and volcanic formations.
Things to do in Malibu Creek State Park include hiking, running, biking, camping, picnicing, fishing and checking out the wildlife. There are over 35 miles of trails and fire roads throughout the park. A fun added bonus is the old M*A*S*H series set, filmed from 1972 to 1983, that resides there.
On a personal note, I love this place. It is beautiful and there and there are roughly 3 dozen different trails, many easy, and some...extraordinarily challenging. such as the Bulldog trail, taking you to 2,500 foot peaks with panoramic views out to the ocean and surrounding peaks and valleys.
Parking for the day at Malibu Creek State Park is currently $12, or you can park at the corner of Mulholland and Las Virgenes and make your way into the park. The park has 62 campsites and 4 RV sites. Visit www.parks.ca.gov/?page_id=614 for more information.
There's also an interesting visitor center about 1/2 mile from the main entrance to the park. It is open on Saturday/Sunday from noon to 4pm, subject to availability of docents. Worth a stop as there are some neat things to see in there, including wildlife and rocks/artifacts and other useful information. You can also purchase drinks in there as well as a small assortment of other items.