You can purchase bottles or glasses of wine in the dining room, although it is pricey. They will also save your bottle for the next time if you don't finish it. Anything you buy on the islands, they will hold until the last nite of the cruise.
"...passengers are permitted to bring one bottle of wine and/or champagne per person purchased in a shoreside location onboard. If the wine and/or champagne is brought to the dining room for consumption, a $15.00 per bottle corkage fee will be applied to the passenger's shipboard account. We prefer that passengers bring wine/champagne no larger than 750ml, however, magnums are acceptable. Wine in a box is not encouraged."
"A truly happy person is one who can enjoy the scenery on a detour."
Carnival Inspiration 2002 Carnival Elation 2004
Grand Princess 2004 NCL Sun 2005
Sun Princess 2006 NCL Dream 2007
Caribbean Princess 2007 NCL Dawn 2008
Island Princess 2008 Island Princess 2009
Golden Princess 2009 Carnival Conquest 2010
Grand Princess 2010 Island Princess 2011
Grand Princess 2011 Carnival Magic 2012
Carnival Dream 2012 Island Princess 2013