I'll be going a cruise in a couple months and with the news lately, I'm thinking that it might be smart to bring along a few items to deal with emergencies like fire or getting stranded on a foreign island waiting on a plane to go home. The cruise line bans weapons, candles, and alcohol and other "dangerous goods" whatever that means. They also limit passengers to two suitcases 16"Hx24"W (no length restriction) and 50 pounds per bag. I plan to have a backpack tucked inside one of my duffel bags and have allotted 25 pounds towards emergency gear for that pack. I can also budget several thousand dollars if necessary for emergency gear.

Is a backpack the right container? Will a backpack work with a life preserver? What would you put in the backpack? Where would you store the backpack during the cruise? Any other suggestions?