Some cruise lines let you bring alcohol on board. This varies but you may be allowed to bring 1-2 bottles (750ml) or a six-pack of beer on board. Check with your specific cruise line though. Some cruise lines don’t allow any alcohol to be brought on board (Costa, Windstar, MSC) and some allow unlimited (Crystal, Regent, Silversea), but most fall somewhere in between. Depending on the cruise line, any alcohol purchased in port will be held by staff until the end of the cruise.