Since 1912, Bay to Breakers has been the day San Francisco lets loose. What starts as a footrace from the Ferry Building to the Ocean Beach becomes something far stranger and more wonderful: a rolling costume party where sea creatures run alongside superheroes, marching bands play from flatbeds, and the sidewalks erupt with spectators. The 12 kilometer route winds through downtown, over hills that punish your quads, and down toward the Presidio. Most people don’t come for the competitive finish times. They come for the elaborate costumes, the community energy, and the specific San Francisco brand of organized chaos that somehow works every year. Start time is 8 a.m. The course gets packed early and stays that way for hours as waves of runners keep flowing. Find a good hill to watch from, or lace up and join the mass yourself.