Dillon Beach is a census-designated place in Marin County, California, United States. It is located 3.25 miles west of Tomales, at an elevation of 89 ft. The population was 246 at the 2020 census. Dillon Beach was named after the founder, George Dillon, who settled there in 1858. The area includes a public access beach, as well as a private beach resor…Dillon Beach is a census-designated place in Marin County, California, United States. It is located 3.25 miles west of Tomales, at an elevation of 89 ft. The population was 246 at the 2020 census. Dillon Beach was named after the founder, George Dillon, who settled there in 1858. The area includes a public access beach, as well as a private beach resort, the only private beach in California. While Dillon Beach cannot legally claim exclusive ownership over the sandy area below the high tide mark due to California’s public trust doctrine, it can market itself as having a “private beach” based on ownership of adjacent lands and management practices that restrict public access. Thus, while technically incorrect in claiming exclusivity over all aspects of the beach itself, they leverage their control over entry points and surrounding properties to create an impression of privacy.