I was on a Carnival Cruise Lines a couple of weeks ago, and after I embarked- I had to go to the office to ask this man a question regarding flight information-anyway...there was a couple in there arguing with a carnival rep that the guy had acceptable ID, and the woman had an expired passport. They wouldn't let her on. The guy was furious because apparently it was a family cruise and his whole family was already on there, and he didn't want to go on without his girlfriend. I never found out what happened, but I looked for them on the ship and I didn't see either of them. SO-Be safe and bring a Birth Certificate and anything else lying around.