Prohibition came into effect with the on January 15, 1920. Besides the business opportunities seized by criminal elements, others found ways to profit from the ban on booze, too.
This article from the Milwaukee Journal reports the “first of dry America’s floating ‘wet spots,’” a Great Lakes vessel turned into a ship that would make three winter trips a week between Miami and Havana. Once past the three-mile limit, there would be plenty to dink. The fare was $35, presumably not including drinks.