On all Carnival ships, the drinking age for ANY alcohol, including wine and beer is 21.
CarnivalSensation February 2015
Carnival Dream November 2015
Carnival Fascination April 2014
Carnival Elation March 2011
Carnival Imagination Sept 2007
Carnival Sensation Dec 2006
RCI Sovereign of the Seas Sept 2006
Carnival Miracle Sept 2005
Carnival Glory Sept 2004
Carnival Fantasy Jan 2004
On Carnival it is 18 to gamble and 21 to drink any type of alcoholic beverage including beer. You S&S card is coded and it will not accept payment for any alcohol so you will not be able to buy it.
For the record... If someone buys someone Under 21 a drink, the workers don't care at all... Yes, you can not buy if your under 21, but if someone buys for you, nobody cares (bare in mind i'm talking about older teenagers 18,19, and 20. Obvisliy if someone bought for a 12 year old I would hope they would say something).