Infants sailing on board a Norwegian Cruise Line vessel must be at least six months of age. However, for voyages that have three or more consecutive days at sea, the infant must be at least 12 months old. When on board, a minor is defined as an individual under 18 years of age at the time of embarkation.

On Norwegian Cruise Line (NCL), the definition of a "child" depends on whether you are looking at safety rules or pricing. For pricing and promotions (such as "Free at Sea" or "3rd and 4th Guest Free"), a child is typically defined as anyone between the ages of 2 and 17. Children under 2 may fly or sail at a further reduced rate or for just taxes and fees. For safety and boarding purposes, a "minor" is anyone under the age of 18, while a "young adult" is aged 18 to 20. NCL has strict rules regarding stateroom occupancy: guests under 21 must usually be accompanied by a guest 21 or older in the same or an adjacent cabin. Additionally, infants must be at least 6 months old to sail, or 12 months old if the itinerary includes more than three consecutive days at sea. Always check specific "Kids Crew" age groupings, as they often divide children into subsets like 3–5, 6–9, and 10–12.