Zahavasdad………….
Not all Cruise lines offer airline style kosher food, many do so but not from all ports. Imagine the horror of showing up for your first meal after the ship has left port and finding out the kosher food didn’t make it…it’s not like a flight that lets you off in less than 24 hours.
There are two River cruise companies in the USA, but they do not offer kosher food options, as they cook and serve family style. We happen to be friends with the owners of both lines, one is based in CT and the other in RI.