This enigmatic San Francisco hideaway maintains its secrets well, with even its entry method shrouded in mystery for those determined enough to seek it out. The speakeasy's elusive nature has only heightened its allure among cocktail enthusiasts, earning an impressive 4.7-star rating from those fortunate enough to discover its concealed location. True to its name, this clandestine establishment ebbs and flows like the city's famous fog, appearing only to those who know where to look.