From The CA State Parks site

San Onofre State Beach features 3.5-miles of sandy beaches with six access trails cut into the bluff above. The campground is along Old Highway 101 adjacent to the sandstone bluffs. The beach is popular with swimmers and surfers. The park includes a marshy area where San Mateo Creek meets the shoreline and Trestles Beach, a well-known California surfing site. Whales, dolphins and sea lions can be seen offshore from time to time. The park’s coastal terrace is chaparral-covered.

San Onofre includes San Onofre Surf Beach - a day use facility, San Mateo campground and day use facility, and a Nature Trail that starts at San Mateo Canyon and leads to San Mateo State Preserve/ Trestles Beach