Rum Runner Flask for crusies?

Don’t bother with a flask, cruiseships won’t let you carry them with you anyway. Get a plastic already mixed bottle or plastic bottle of rum and put it in your checked in baggage. The cruiselines thoroughly check your carry-ons. If you bring on the rum in a plastic bottle the airline won’t break it in your luggages and you can get fruit juice or soda at the bar and bring it back to your cabin then mix it. You can then carry your drink pretty much anywhere with no questions asked. Don’t leave your bottle of rum out in the open, the cabin stewards are nice to you but they do have a job to do and it is easy enough to leave it somewhere where they won’t see it easily.

Been there done that a few times, it’s a learning experience.