on the carnival website:
Bringing Liquor and Beverages On Board - Embarkation
Guests are prohibited from bringing water, sodas and other non-alcoholic beverages that are packaged in glass or plastic bottles.
On embarkation day, a small quantity of non-alcoholic beverages (i.e., sparkling water, sodas, energy drinks, juice, and milk), packaged in cans or cartons, may be brought on board and must be in the guest's carry-on luggage. A small quantity is considered a maximum of 12 sealed, unopened cans/cartons of 12-ounces/354-ml each or less, per person.
Guests are prohibited from bringing alcoholic beverages on board with the following exception - at the beginning of the cruise during embarkation day only, guests (21 years of age and older) may bring one 750-ml bottle of sealed/unopened wine or champagne, per person, in their carry-on luggage. Outside this exception, all liquor, beer, other forms of alcoholic and non-alcoholic beverages are strictly prohibited in both carry-on and checked luggage and such items will be confiscated and discarded and no compensation will be provided. Guests sailing with us on back-to-back cruises are entitled to bring the same quantity as stated in this policy, per cruise. The additional quantities will be stored for safekeeping at the start of the first cruise and will be given to the guest as each following cruise begins.