I think those are San Diego Electric Railway "suits" posing at the left for photographer L. K. Dewein on July 21, 1924. The streetcar is on 3rd Avenue, just south of Broadway. Horton Plaza is out of sight at the left. The word has always been that Spreckels built Mission Cliff Gardens so people would ride his streetcards to get there. I believe he built Mission Beach Amusement Center (today's Belmont Park) for the same reason. I'm wondering where folks swam at Mission Beach in 1924. I'm not sure the plunge was even open yet. Perhaps a bracing splash in the ocean.