Although Carnival's policy is no alcohol, I brought several minis in my checked luggage and probably could have taken an entire bottle if I wanted. You can also bring wine on board. I wouldn't try to bring alcohol on board in your carry-on bag, though.
You can buy alcohol in the ports. Some shops will send it to the ship for you and you will get it at the end of the cruise. If you try to carry it on, they supposedly will confiscate it and give it to you at the end-- however, this was not the case for us as we carried 2 750 mL bottles of Absolut right on the ship! I think that may have been a fluke, though. Anyway, my mom and I brought back 4 bottles of liquor total, so you can definitely bring some back-- how much depends on your Customs allowance.
It has been my experience, (2 Carnival - 1 Royal Carribean), since 9/11,
the more you try to hide it, the more likely you will get it confiscated.
Four of us brought 1 bottle of champagne each in carry-ons last october.
My T/A, had 4 bottles confiscated at the pier, returned to him outside the twelve mile limit. Don't try to hide it too much, don't act like your hiding something, don't look guilty,
just play ignorant. They don't want to harrass you, but they have rules to follow.
Our group of 16 just returned from the Pride. Each one of us packed 4-5 bottles of spirits in our checked luggage. There was no problem. We all set up little "bars" on the counter tops in our rooms with mixers, etc. We always had fresh ice supplied bu our cabin stewarts. One person even brought a blender for mixed drinks. This sure saved us all quite a bit on our bar tabs.
I like to drink Absolute, so I just saved a big Scope bottle, and added my Absolute and a little blue food coloring viola! I carried it on in my toiletries bag with not a second glance. When the bag passed through the xray machine security asked to look inside. The security officer held my bottle of "scope" in her hand while she searched my bag. The heavy discount on the duty free liquor more than makes up for what you spend in drinks. The drink prices are about the same or less than you would expect to pay in a popular nightclub. The drink of the day is about $3.50 a bucket of 4 beers is $13(including tip) and who wants to run back and forth to your room to replenish your drink?
If you wanna save..hit the cocktail parties...free liquor!!