High Quality Content by WIKIPEDIA articles! Del Mar is an upscale beach town in San Diego County, California. The population was 4,161 at the 2010 census, down from 4,389 at the 2000 census. The San Diego County Fair is hosted on the Del Mar Fairgrounds every summer. Del Mar is Spanish for "of the sea" or "by the sea", because it is located on the Pacific Ocean. Colonel Jacob Taylor purchased 338 acres (1.37 km2) from Enoch Talbert in 1885, with visions of building a seaside resort for the rich and famous.