Yes, a single parent can absolutely take a child on a Carnival cruise, but there are specific documentation requirements to ensure a smooth boarding process. If the child is traveling with only one parent and they do not share the same last name, Carnival (and border officials) will typically require you to present the child’s original birth certificate or passport to prove the parental relationship. While Carnival itself does not strictly mandate a notarized "Minor Travel Consent" form if at least one parent is present, it is highly recommended to carry one, especially for international itineraries. This is because officials at foreign ports of call or airline staff on international connecting flights may demand proof that the other parent has consented to the child leaving the country. If you are a divorced or separated parent with sole custody, it is also wise to bring a copy of the legal custody agreement as a precaution. Ensuring you have these documents prevents any potential delays or denied boarding situations during the check-in process at the cruise terminal.