Sea state matters, as does the size of the vessel in the sea state. Even
so, the first cruise I ever took with my wife to be was a large
passenger ship where the sea state was mill pond. She was very, very
sick. But that was it. Our honeymoon was eleven days at sea on an even
larger ship in some horrendous weather where the ship clnaged like a
gong and we have been sailing on our own boat for years. Never another
problem for either of us thugh we have had the occasional guest for whom
the day was no fun at all. Even busted up one romance. He got sick; she
did not.