For some folks wanting the ideal getaway vacation, there's nothing more serene than a week-long cruise in the Caribbean, the Pacific or other exotic bodies of water. A ship holiday certainly is a lot more comfortable than getting into sardine mode on cramped planes serving food more at home in a trough than on a tray. And a resort or hotel might raise some paranoia about staying in a country where a foreign language is dominant and an innocent gesture might turn into a costly cultural violation.

All of these modes and accommodations aren't cheap even by bargain-hunter standards. And like any other sojourn, cruise ships also have their own ways of doing business which can be executed at the expense of their guests. It's a no-brainer considering that the three biggest revenue streams for a cruise company are fares, alcoholic beverage sales, and casino coffers and more aggressive lines will go to no end to rake it all in.

That includes services that you thought might be provided onboard until you find out that those amenities are too costly for a ship to provide—or are available for a fee unknown to you until you get the final tab.

Related: Here's Why Alcohol Is Not Included In The Price Of A Cruise

You won't get the cabin you want

Cruise ship cabin exteriors and interior
CNBC/Cruzely

It's well known that cruise fares can vary according to what type of cabin you choose and where it's located on the ship. When it comes to booking, you'll likely be told that if you want a cabin with a balcony or window facing the oceanic scenery, you'll be paying a bit more than one that's more "inside" and leave it at that. However, you actually have a lot more options than that.

First, because of the ship's contours, cabins located at the front and the rear will have a different layout than those located mid-vessel; beyond that, those sizes vary from liner to liner. Also consider that cabin prices rise according to deck level, with bottom decks being the cheapest, which are bad choices to guests highly prone to seasickness.

Also, watch out for prices on cabins that are on the same floor, but may still vary according to activities that might disturb your sleep. If it's cheaper to pick a room in the rear of the ship, those saving might be countered by endless engine noise directly below you. Others in the middle may be stuck near kitchens, dining rooms, bars, and elevators all sources of annoyance even during the wee hours. And folks who booked the more expensive top-level suites near the front of the boat will likely complain about all the revelry in the pool area.

Before you book, ask for a ship deck plan before choosing a cabin.

There's a lot of free stuff that isn't really free

Carnival cruise bartender serving drink
EZ Travelpad

When you're given the price of a cruise before you head off, you'll likely assume that a lot of services and items are included in the bill. That's where most guests get into trouble when they realize how much extra they'll need to pay.

It's a given that alcoholic beverages are expensive, but teetotalers hoping to save a bundle guzzling on free soda and bottled water may change their minds since they could be charged at least $1.50 for those refreshments. Juice and water available in jugs, however, is available at no cost. Also, be wary of certain menu items at the free buffet. Some entrees like filet mignon and seafood dishes may carry extra charges as high as $30.

Want to check out the spa, fitness center and the adults-only lounge by the pool? There's also a charge for those. And forget about free Wi-Fi, as most cruises charge by the minute offering a service considerably slower than the one you have at home.

If you need some adult alone-time, babysitting services are free except for late nights, when an hourly fee is charged. For the most part, room service is still free, although some cruise lines do charge if particular food items are ordered or if the staff is summoned at night. And if you feel generous tipping the folks, there's a good chance a gratuity of at least 15 percent is already built into those hidden charges.

Where you could get soaked the most

Family dining on cruise ship
Tips for family trips

Besides those hidden dining room costs, you're not likely to improve your vacation budget bottom line if you bring your own booze on board. You could get hit by a corkage fee as high as $30 if you bring a bottle with you to the dining room. That charge won't apply if you choose to swill the good stuff in your cabin, though. Also, be advised that the cruise does have a limitation on how many bottles you bring on board; a suitcase full of Jack Daniels is certainly going to interfere with the ship's alcohol revenue stream.

And when you finally get your bill, watch out for additional charges that went into effect regardless of how thrifty you chose to be on the cruise. In this case, we're talking about foreign and domestic taxes, customs fees and docking and port charges that depending on your destination could bump the cost of your trip from $100 to $300. Besides embarking on and disembarking from your voyage, those additional costs are also tacked onto any excursions slated as part of the cruise ship's route.

No such thing as the law of the land at sea

Exterior of ship deck at night and captain on deck
Instagram/Cheat Sheet

First, it should be pointed out that cruise ships today are safer than ever, so avoid those notions of your vessel hitting an iceberg or getting capsized by a gigantic tidal wave. Those aren't even remotely likely to happen. But be advised that when it comes to security and legal protection, you're cruising in international waters, so enforcement of particular laws is murky at best.

For openers, be prepared to get ripped off in the casinos, since there's no commissioning board that a ship has to answer to. Realizing that, the staff is particularly sharp at taking novices for a costly ride.

And while every cruise ship has a security detail, thefts and other petty crimes are still common. Cruise companies are seldom forthcoming in revealing statistics about that type of activity. More serious crimes onboard are also given the same treatment, which usually results in authorities in countries of the victim's origin are notified.

How those issues have been dealt with is unclear, but what we do know is that crimes aboard cruise ships have risen by 67 percent between 2018 and 2019. Still, most pundits claim you're ten times more likely to become a victim on land than on a pleasure boat.

Next: Things You Should Know Before Booking A Cruise