* Casilda: The daughter of the Duke of Plaza-Toro, she is in love with Marco, one of the gondoliers, and believes him to be the rightful King of Barataria.
* Gianetta: The daughter of the Duchess of Plaza-Toro, she is in love with Giuseppe, another gondolier, who she also believes to be the King of Barataria.
The operetta revolves around the confusion caused by the two gondoliers being mistaken for the lost princes of Barataria, and their subsequent marriage to the two daughters of the Duke and Duchess.