Whether a passport is required for an AIDA cruise depends on the specific itinerary and the ports of call. Generally, for international cruises, it is advisable for guests to have a valid passport. This is particularly important if the cruise includes stops in countries outside the guest's home country. Some short cruises or those that only visit ports within a certain region may allow travelers to board with other forms of identification, such as a national identity card. However, AIDA recommends checking the specifics of your itinerary and the entry requirements for each port of call. Additionally, it is always a good idea to verify documentation requirements on the AIDA Cruises website or in the travel information section for the most accurate and up-to-date guidance.