Spare batteries seem like a good idea even with energy sipping LED lights but I've started shifting to toward putting in fresh set of high-capacity lithium cells, AA or AAA cells, and foregoing the bulk and weight of the spares.

I wouldn't be worried about bulk or weight with a suitcase on a cruise ship. I use lithium AA's too.

Just a thought about batteries; If you can, arrange your electronics (flashlight, radio, cell phone emergency charger, etc.) so they all run off of the same 1 or 2 sizes of batteries. It cuts down on the cost and bulk of the spares since you're not buying different types for each device.

Also, consider water purification tablets. Though they're more suited to airtravel and utilities problems then cruise ships.

I think one of the smaller solar /crank radio/ phone charger/ flashlight units would be useful. Amazon has them for $20 -30

Unless it has HF/Shortwave, not sure how much use a radio would be. A small solar battery charger might be nice to have though, with four NiMH AA's you could keep going indefinitely. But that amount of weight/space would store a lot of Lithium AA's.

Its been many years since I've been on a cruise but even then I remember security as being pretty strict.

A flashlight and spare batts goes without saying. There's plenty of food on board, so maybe start a small stash of snacks and water from the buffet?

That's sharp -- build a cache after boarding.

I have actually been on several cruises in the western Carribean and enjoyed them. An incident like this would definitely ping the suckage meter, though. As far as bringing stuff on board, I have found security to be less strict than at an airport. There are metal detectors at the port entrance, and checked baggage is supposedly x-rayed, but I didn't see that happen. I know there are no drug dogs sniffing stuff when boarding, because the smell of burnt marijuana was quite evident on several occasions once we were underway. I placed my large folding knife, lighters, etc, in my checked baggage and took it out when the bags arrived at the room. I saw several experienced travelers openly place 24 packs of bottled water and packaged snacks with their baggage and no one batted an eye. bottled water and snacks are available on board, but are expensive. If you are leary of trying to carry it in, bring some empty bottles and fill them in your cabin. The onboard water is palatable, but I would have some drink mix for taste. Or just plan for the expense and buy the stuff as soon as you're aboard.

I always have a headlamp and secondary flashlight when I travel, spare batteries, and clothes for one "season" colder than what I expect to encounter, a knife, and charger for the cell phone, and some baby wipes. I am considering a small solar powered radio. All of which would have been nice for this type of incident. The one thing that boggles my mind about this particular incident is the fact that there are no independant generators on board to power refrigeration and emergency lighting, plumbing, etc. Surely someone envisioned this kind of thing when designing a cruise ship? Unless the Captain banned it, I bet alcohol sales went up sharply!

As several have mentioned, a flashlight seems practical and useful. As for lugging a bunch of other stuff on a cruise I'll pass. Anybody who is so apprehensive about cruising that they they want to carry a bag of survival gear, should just stay at home or find another way to travel. It makes about as much sense as carrying a parachute on a commercial flight IMHO. And yes, I have cruised before - a two week Alaskan excursion.

Heresy!! ;-)