Unless you've booked a large suite, your cabin will be compact, and you'll want to make sure your suitcases will fit under the bed after you've unpacked them. Thick, hard-sided suitcases will not fit, but pliable duffel bags always will; consider packing in them.

Just because a cruise is a cashless society — everything gets charged to your onboard account with the swipe of your all-in-one room keycard — doesn’t mean you won’t need any dough in port. If you plan to explore on your own, grab a snack or lunch, or do some shopping, you’ll need cold, hard cash.

OK, this might seem a little crazy as there will be more food on your cruise than you can possibly consume in a million years, but if you absolutely have to have your favorite brand of power bar, chocolate, or chewing gum, bring it with you. Cruise ship gift shops usually have a limited selection of snacks.

An actual old-fashioned book or two made of paper may fare better than a pricey iPad or e-reader when you're sitting by the pool within splashing distance of cannon ball contests. Plus you won't have to angle it just right to avoid sun glare. A book is also less likely to be nicked if you want to save your chaise lounge with it.

A few of these buggers will help your clothes stay in place if you have a balcony and want to air-dry your wet bathing suit or items you hand-washed in your bathroom sink.

Not all cabins have minifridges, so if you’re cruising with young kids who like chilled drinks or snacks, bring a small cooler you can keep filled with ice from the cabin staff or the buffet restaurant.

A roll will be indispensable — from jury-rigging a torn hem on a dress or skirt to taping closed a banging dresser drawer (remember, the ship moves!) to keeping the lid to your sunscreen tightly closed in your beach bag.

Many ships have theme parties on the open decks or in the nightclubs. Consider packing a tropical shirt or grass skirt for the popular beach parties, and an eye patch and bandana in case there’s a pirate night.

If you’ve got a baby in tow (and considering many cabins only have showers and no tubs), it’s a breeze — not to mention hygienic — to give baby a bath by plopping junior atop a large sponge on the shower floor before soaping him or her up.

If you’ve got one of those nifty lightweight foldable bikes (the lightest weigh less than 25 pounds), pack one to pedal around bike-friendly ports like Barcelona and Amsterdam.

Whatever portable musical instrument you may play — banjo, guitar ... accordion maybe? — bring it with you and join the popular passenger talent shows many lines organize.