Almost every cruise passenger has experienced the "why didn't I bring it" moment at some point or another. After hours of strategically packing your bag with items to curb shipboard expenses, it's easy to overlook how add-ons (think poolside cocktails and spa treatments) and other extras can leave a major dent in your vacation budget. Don't fret: With a bit of planning, cutting costs is possible. Before your next cruise, maximize your savings with this list of money-saving items.See: The Best Carry-On Luggage of 2019It may seem like a no-brainer, but even the most avid cruisers forget to pack sunblock. Not only is sunscreen more expensive on board (typically priced at around $12.95) the selection is more limited than your local drug store.There is a commonly told story of a seasoned cruiser who, before every cruise, buys a small, used suitcase and stuffs it with bottled water. On boarding day, the hapless suitcase goes through checked luggage. After the cruise, it's left abandoned in the passenger's stateroom for the room attendant.While this approach may seem a little extreme, bottled water can cost up to $4.95 per liter per day on mainstream cruise ships, which may or may not include a 15 percent gratuity. You can avoid racking up a hefty bar tab by bringing your own water aboard. This is also one item that costs less in port and there's usually no problem carrying water back on board.If an international cruise is on the horizon, go to a major bank and convert your dollars to euros, pounds, francs or whatever currencies you'll be using for the locations on your itinerary. You'll avoid high commissions at the onboard purser's desk and confusion at a currency exchange overseas.So how much money should you bring with you? Enough to get you through the first couple of days, taking into account port dining expenses and taxi fares. While most cabs and restaurants accept credit cards, it's nice to have local currency on hand (in a secured pouch or wallet, of course).See: Best Cruise Lines for the MoneyThis item doesn't take up much room in your packed suitcase. The flat-folding bag should have small wheels or a loop to piggyback onto your main suitcase. Avoid a frenzied shopping crunch on the last night when everyone is buying flimsy and overpriced tote bags at the ship's gift shop. While soap won't be hard to come by on board, your best bet for saving is packing your own. Many mainstream cruise lines, including Carnival, Royal Caribbean and Norwegian, now feature wall-mounted generic liquid soap dispensers in the shower. The same goes for shampoo and conditioner. Unless you want to pay double for these items at the gift shop, bring your own.If you've been thinking about buying a new camera on board because you heard that the prices are reduced, think again. Careful comparison shopping between hometown and shipboard camera prices show that you'll find a better price and more selection on land than at sea. This will also give you some time to learn how to use your new gear.If you're still toying with the idea of picking up a new camera while aboard or at port, do your research well in advance of your trip and write down the exact items and prices. That way, when browsing for the best technology, you can reference the comparable price at home. But be aware that many Caribbean electronics stores do not match Internet prices from major camera dealers in the U.S.Even if you don't think you'll be taking many photos on your cruise, it's a good idea to bring extra SD memory cards with you. If you prefer a particularly roomy card with 32 gigabytes, there's a good chance that the ship won't have it. Plus, some cards sold overseas may not be compatible with your camera or device. (It's no fun to have a card self-destruct in your camera and erase all your trip photos.) Almost all cruise ship gift shops sell batteries, but as with most items on board, they will cost more than at a store back home.See: 7 Things You Didn't Know You Could Do on a CruiseNo matter when the munchies hit, having your own snacks in your cabin is the cost-effective way to go. A trip to the gift shop or candy store can become costly and you'll probably end up buying something that you wouldn't buy at home, anyway.Pack a can of assorted nuts, chips or popcorn. This is crucial if you are traveling with kids. Healthier and often better than the selection on the ship, snacks from home can save the day. Though most major cruise lines allow one bottle of wine per person to be carried on board, some cruise lines, including Royal Caribbean and Celebrity Cruises, charge a steep corkage fee in the dining room. Corkage fees can range anywhere from $10 (on Azamara Club Cruises) to $25 (on Royal Caribbean and Celebrity). Norwegian even charges the corkage fee to your onboard account at embarkation. Before you set sail, review your cruise line's FAQs to brush up on whether you are allowed to bring wine or spirits on board. And if you want to sip in the privacy of your stateroom, don't forget to pack a corkscrew. No traveler likes to waste money, especially when extra costs could have been avoided. Whether it's your first or 50th cruise, the less money spent on board for things that you could have packed from home, the more you'll enjoy your vacation. See: 9 Tricks to Saving $100 on Your Next CruiseSherry Laskin hasn't set foot on an airplane in over 20 years and relies on ships, boats and trains to explore the world. Her cruise and travel site CruiseMaven covers everything you need to know for a cruise vacation; from planning and packing to dining and destinations across the globe. You can follow Sherry's cruise adventures on Twitter @CruiseMaven, Google+, Facebook and Instagram.