San Francisco's famous 12k run that features a blend of competitive runners and participants fully decked out in costumes, all while spectators party along the course—was held on Sunday.

What do inflatable rubber ducks, tipsy popes and a space-bound Katy Perry all have in common? They were among the flashiest costumes at Sunday's Bay to Breakers, a 12K and 15K race stretching all the way from downtown San Francisco to where the ocean meets the Great Highway.

San Francisco’s streets transformed into a sea of color and costumes as thousands ran, danced, and paraded across the city for the iconic Bay to Breakers.