Your best bet is to pick up some water on the way to Port Canaveral. There are many retail stores only minutes from the port. You can buy a case or two of water, give it to the porter along with the rest of your luggage and he/she will bring it to your stateroom.
The cooler that was spoken off was probably the one in the stateroom which is not portable. The cooler is the size of a small refrigerator which is installed in most rooms in a cabinet below the TV. It can be used to store cold items, but isn't very effective at cooling drinks, etc. If you added ice to the cooler that would help, but again it is not a refrigerator.
You can ask for a refrigerator to be placed in your stateroom, but most that are available are reserved for people with medical conditions that need to store there medicines in a refrigerator, so you can ask for one, but don't be surprised if there are none available.
Regardless (excuse the tangent) you seemed more interested in a cooler to take to the beach which I am not sure you can bring with you onboard. I know this was covered before and I believe there is a size limitation on the size of a hard-sided cooler, so your best bet is to bring a soft-sided cooler you can pack in your luggage and fill it up on a daily basis as needed.
You can buy water onboard, but buying a case at
Walmart is so much more cost-effective.
Jeff