There’s no “open beverage” rule onboard. You can bring drinks from a bar or buffet to your cabin or elsewhere on the ship and no one will bat an eye. (Same goes for food.)
Open container law on Cruise ships is in effect. Just like in Key West and Savannah GA – you can walk around with a beer and it’s not a problem.
What other secrets to enjoying a cruise ship experience? This link has over 20 tips like this one.