Having your correct passport number on file with the cruise line you are traveling with is vital. If you initially registered a passport and it has expired or you have applied for and gotten a new one with a different number, you have to update the cruise line with the new information. Remember that your passport MUST be valid at least 6 months from the expected date of return from your trip, or you can be refused entry into other countries.
The main reason it is important the cruise line has your passport number, is that the company has to provide it on the manifest to the countries we are visiting for customs and immigration. The one you have in hand at the pier MUST match the records they have on file for you. If it doesn’t, you will be refused boarding because they can not change the manifest within 24 hours of departure. All you have to do, is log into your profile of the cruise line you are sailing with, and update your account with the new passport number you were issued, so the numbers match. The other option you have besides doing it yourself online, is to call the cruise line directly and give them the new passport number.
When I travel, I always bring a photocopy of my passport, so I can leave the original in the safe in my stateroom, and then I bring my photocopy with me into a destination with my credit card, my sea pass and my drivers licence. This way I do not have to worry about the passport, if my bag is lost or stolen. On this paper, I include phone number details about the ship and emergency contact information that the cruise line will provide to you in their daily newsletter which is specific to the port we are in.
All cruise lines need to have a credit card on file for them to set up your onboard account. The day of embarkation, they attach your sea pass card to it, so that your room key card acts like your credit card as well. Any charges onboard, from cocktails, earrings or headache remedies, go directly to your credit card as ships do not accept, debit or cash. In regards to your credit card and the cruise line: with your credit card, you have the option of providing the number on your online check in your profile as well. You can prepay your gratuities so you begin your trip with a credit on your onboard account, as cruise lines can only add gratuities daily and not as a one time charge.
The cruise line will ALWAYS confirm that the card you used online, is the same one you want to use when you check in with them at the counters. If you care to change it, this is when you would provide the Cruise staff with the alternative card. So be prepared to show them the credit card you want to use while onboard, along with your e-documents when you check in, on the pier.