To be sure, Carnival gift cards aren’t the only cruise line gift cards you can buy on sale. As an example, Royal Caribbean ...

Passengers can order special occasion gifts and stateroom décor packages through Carnival’s Fun Shops prior to their cruise. Some passengers also suggested bringing along your own decorations ...

towards the purchase of a Carnival cruise, activities/shore excursions, and redeemed onboard toward the Sail & Sign account for gifts, drinks, and fun," according to Newegg’s website.