The official statement from Carnival, as posted above, is to be taken with a grain of salt. We carried a cooler on for our 7/27 cruise on the Conquest and had no problem. It contained 12 24oz diet cokes, a dozen or so bottles of water and two kinds of wine. The cooler is large and we had it full. We were hoping to be able to send it with our luggage but the porter said they don't allow that and it's a good thing anyway the way the pier personnel throw the luggage around. So we carried it on and at security we were asked to open it and they looked in and said ok carry it through the metal detector. Very easy.