What family legal documents do I need to board a Royal Caribbean cruise ship?

Should the last names of the parent and minor child traveling with them differ, the parent is required to present the child's valid passport and visa (if required) and the child's birth certificate (original, a notarized copy or a certified copy). The name of the parent(s) and the child must be linked through legal documentation.

Adults who are not the parent or Legal Guardian of any minor child traveling with them are required to present the child's valid passport and visa or the child's birth certificate (original, a notarized copy or a certified copy) and an original notarized letter signed by at least one of the child's parents. The notarized letter from the child's parent must authorize the traveling adult to take the child on the specific cruise, must authorize guardian to sign legal documentation/waivers for participation in any activities requiring them (i.e. Rock Climbing, Flowrider, Bungee Trampoline, Inline Skating, or Ice Skating) and must authorize the traveling adult to supervise the child and permit any medical treatment that must be administered to the child. If a non-parent adult is a Legal Guardian, the adult must present a certified certificate of Guardianship with respect to the child.