Under the 1961 Convention on the Reduction of Statelessness, for the purposes of determining the obligations under the convention, a birth on a ship or aircraft in international waters or airspace shall be treated as a birth in the country of the ship or aircraft's registration.

Being born on a cruise ship in 2026 triggers a complex "citizenship cocktail" that depends on the ship's location and registration. Under the principle of jus soli (right of soil), if the birth occurs while the ship is within the 12-mile territorial waters of a country like the United States, the baby may be eligible for that country's citizenship. However, the most common outcome is determined by jus sanguinis (right of blood), where the baby automatically inherits the citizenship of its parents. Additionally, some countries follow the "flag of convenience" rule, where a child could theoretically claim citizenship of the country where the ship is registered (e.g., Bahamas or Panama), though this is legally difficult to enforce. From a logistical standpoint, the ship's doctor will issue a "Record of Live Birth," but the parents must register the birth at the next port of call with the nearest embassy to receive an official birth certificate and travel documents for the infant.