Carnival strongly recommends purchasing trip cancellation insurance.

Carnival's cancellation policy varies based on the length of the cruise and the time before the sailing date when the cancellation is made+---. Generally, there are no cancellation fees if you cancel before final payment, unless you booked a promotion with a non-refundable deposit+---. For cruises shorter than 6 days (excluding Alaskan, European, Transatlantic, and Panama Canal cruises +---), a deposit is required for cancellations made 75-56 days prior to departure, and 50% or the deposit is required for 55-30 days prior to departure, whichever is greater+---. For longer cruises or special routes, the deposit is required for cancellations made 90-56 days prior to departure.
Specifics:

2-5 Day Cruises (Excluding Alaskan, European, Transatlantic, and Panama Canal):
Up to 76 days before departure: No cancellation fees (except for fares with non-refundable payments).
75-56 days before departure: Deposit is the cancellation fee+---.
55-30 days before departure: Deposit or 50% of the total fare, whichever is greater.
29-15 days before departure: Deposit or 75% of the total fare, whichever is greater.
14 days or less before departure: 100% of the total fare.
6+ Day Cruises and Alaskan, European, Transatlantic, and Panama Canal Cruises+---:
Up to 91 days before departure: No cancellation fees (except for fares with non-refundable payments).
90-56 days before departure: Deposit is the cancellation fee+---.
55-30 days before departure: Deposit or 50% of the total fare, whichever is greater.
29-15 days before departure: Deposit or 75% of the total fare, whichever is greater.
14 days or less before departure: 100% of the total fare+---.

Important Notes:

Carnival strongly recommends purchasing trip cancellation insurance.

Cancellation charges for group bookings, partial ship charters, or full ship charters are determined by the charter contract or group booking agreement+---.
If Carnival cancels or significantly delays your cruise, you may be entitled to a refund under their Nonperformance of Cruise Refund Policy.