From the Princess Passage Contract & enforcement may vary.
Guests are also prohibited from bringing water, sodas and other non-alcoholic beverages on board that are packaged in bottles. A small quantity of non-alcoholic beverages (i.e., sparkling water, sodas, juice, milk) packaged in cans or cartons may be brought on board on embarkation day, only if carried on in Guests’ hand luggage (not in checked luggage). A small quantity is considered a maximum of 12 sealed, unopened cans/cartons of 12 ounces each or less per person. Guests will be asked to discard open beverages in plastic containers prior to boarding.
All checked and carry-on luggage will be scanned and any prohibited items, including alcoholic/nonalcoholic beverages will be removed, confiscated, and discarded. If Your luggage is locked, the lock may be removed by security or, alternatively, the luggage will be held by security until You can be present for an inspection and any items in question further identified and/or surrendered.