Beginning February 18th new rules implemented by the U.S. Department of Customs and Border Protection will require all cruise ships departing from U.S. ports to submit a passenger manifest to them no less than 60 minutes before leaving port. What this means is that all passengers have to be on board and checked in before that.<br /><br />Some lines such as Royal Caribbean, Celebrity, Regent, Crystal, Oceania and Princess have introduced policies that require passengers to be on board at least 90 minutes prior to departure. If they arrive late, they may be refused boarding. NCL has implemented a 60 minute rule but advise passengers to arrive at least 2 hours prior to sailing.<br /><br />It's usually a good idea to get to the pier as soon as possible.  Even though most lines state a boarding time, it really depends on how fast they can get the passengers from the previous voyage off and start the turnaround.  I've always arrived 3 to 4 hours early and have never had to wait until the stated boarding time.  If you're flying in, I'd recommend arriving the night before but if that's not possible, make sure you have a several hour window to get to the pier.  You never know when or why a flight may be delayed.