I was only saying that, because I was only worrying about you getting your self into trouble, about flying over a cruise ship. I am sorry if it upset you. You are in control of your decisions.
There you go, innocent question, but easily misconstrued the way it was put forward.
I believe it's ok to fly near these ships, but I'd personally not fly over them, or too close in front of them in motion (leaving port etc).
We can't fly over busy places (Australia) people, vehicles etc, not even one person not involved in the flight (within 30m / 100' in fact !), and certainly it'd be hard to get a cruise ship in port without someone on deck.
In the US I believe the rule is no direct flight over a person, so you can fly close, but not right over.
Not the best rule I feel, drones move, a buffer is a good idea, bt looks like FAA aren't changing this so you have some freedom there (whether sensible or not is another thing).
Edit, always check for NFZs though, these may apply in places when such events occur.