Coronado is a resort city in San Diego County, California, United States, across San Diego Bay from downtown San Diego. It was founded in the 1880s and incorporated in 1890. Its population was 20,192 in 2020, down from 24,697 in 2010. Coronado is a tied island which is connected to the mainland by a tombolo called Silver Strand. Along the coast of Southern California lies four islands that were spotted by Sebastian Vizcaino and his crew. They named them “Los Coronados.”