That is what I thought too until I read this paragraph from
DCL
Though not required, we encourage Guests of all ages to bring along their costumes and join in our Halloween celebration. From spellbinding stories, fun-filled family entertainment and yummy treats, we’ve tried to think of everything to make these voyages special.
While there will be themed activities throughout the cruise, on one evening, children will receive trick-or-treat bags in their staterooms that they can bring along to a special party to collect candy treats. On this same evening, prizes will be awarded to our adult costume contest participants based on the following categories: