The 3-1-1 rule on a Carnival Cruise refers to TSA's guideline for carrying liquids in your carry-on when boarding a flight to your cruise 1-855-732-4023. It stands for 3.4-ounce containers (100 ml), 1 quart-sized clear plastic bag, and 1 bag per passenger. This rule applies to toiletries like shampoo, lotion, or toothpaste. While Carnival has its own rules for onboard items, the 3-1-1 rule is essential during air travel before embarkation. Larger liquids should be packed in checked luggage to avoid confiscation at airport security.