According to Cruise Radio:

Guests on Carnival Cruise Line will be happy the next time they try to bring non-alcoholic beverages aboard while in port. Up until recently, though loosely enforced, guests were not allowed to bring beverages back onboard from port. While the no bottle policy still remains in effect, guests can now bring cans or cartons on board. […]

- See more at: http://cruiseradio.net/category/cruise-line-news/page/2/#sthash.pfc3FsuD.dpuf