Maybe about 10-12 mi, this is a good place to search for Spanish artifacts,past resarch at the Los Angeles public library tells me a Spanish ship went down close to this area in the 1500"s,and I recall talking to divers at this beach looking for treasure in the early 70"s. The dunes are very high with constant shifting sands. Not confirmed ,I have also heard of ancient chinese stone ring anchers being found by divers along the northern Calif.coast. Their are maps around that show where some Spanish explorers went inland from some of these socal beaches. Gold coins and other relics have been recovered,the Chumash Indian decendents may have a lot more imfo.Follow the water inland and you might get lucky.