Cruise weddings and packages renewing wedding vows at sea are possible, but it is subject to strict requirements in order to be considered a legal ceremony.
We would advise you to contact the Customer Service department of the cruise line you are travelling with, in order to discuss the possibility and details of any wedding options, as they all have different options and requirements such as locations and a legally registered person, such as a priest or ship captain, to conduct any weddings at sea.