Is it possible for a cruise line to refuse or disembark a passenger?

It is certainly possible that a cruise line will refuse or disembark a passenger. This is never the starting point, because a cruise company wants you to have a nice holiday. Of course, they also want to ensure that all passengers have a fun and safe time on board.

Do you want to come on board, but you refuse to go through the safety checks, then you will be refused. If you try to bring drugs or other illegal substances on board, the cruise ship will also deny you access. Threats to other guests or to the crew will not be accepted either.