The cruise line will try to sell you excursions at the ports you visit at a high price, sell you extras like portrait photographs, tempt you to gamble in their casino and shop in their stores selling jewellery, watches etc. You can of course choose not to spend any money on things like these.

Cruise line often come with the guarantee they will wait for you if you are late for returning for the ship from a paid excursion arranged by the cruise liner. If you go ashore your self it’s possible you could get left behind if you are tardy.

Alcohol packages often cover basic drinks, if you have a taste for finer things an aged whisky or brandy you’ll pay an excess on your bill in such cases.

There are on some cruise lines premium dining and entertainment options at an extra cost.

Spa treatment, massages etc are extras on many cruise lines, some larger ships with families have adult only areas with cabanas etc. for people who want not to have rugrats spoiling their holiday that you pay to hire.

Tips to staff are expected on many cruise lines, I am British so the cruise lines I book with have tips included in the fares we are too embarrassed to tip in person so.

Internet connections are another way they make a lot of money from you those packages are really steep, but you could have and electronic detox on holiday.

Thanks to Willeke and mKennedy for their suggestions.

There are significant expectations for tips, for at least a dozen people/roles, with 'recommended daily' amounts.
For a seven-day cruise, you are expected to drop around $ 300 in tips (per person), and although can of course ignore that and give nothing (or less), they are pretty good in making you feel obliged, and they often make it cumbersome to even reduce it by $ 1.

For example, they charge the 'recommended tip' automatically to your credit card on the day of arrival, and if you want to give a different amount, you have to go to a service desk and have it changed (where a lot of people are in a long line for all kind of things...).

Furthermore, you need to get to the ship, so typically you need to park your car there, which they offer for 20 or more $ per day. Don't hope for simply parking 'somewhere nearby' and walking a bit, you are not the first one with that idea. At least five miles around every square foot costs about the same for parking. It is best if you have a friend drop you off (and pick you up).

Connections from the nearest airport are also offered at significant cost - but it might be cheaper than renting a car and paying to park it, or taking a taxi.

The rule of thumb from experienced 'cruisers' is to expect to pay about double what the sticker said, if you are a bit clever with the worst tricks.

As an experienced cruiser, who tips well, I find cruises to be an extra ordinary value. In fact your cruise might cost a bit less than what you actually paid! You could be refunded part of your port fees if the boat leaves a bit early. However, you will likely spend more than that.

Deferring to other answers I will give my insights.

I prepay my tips and also tend to tip extra when I get good service. To me, the tips, are part of the cost of the cruise. Most of those people work their tail off for you, and that is how they make their money. This past cruise I tipped the wait staff extra, because they were very kind/helpful to my wife's food allergy and our cabin steward because we asked for a couple of extra things and he was great.

We tend to use the ship supplied shore excursions despite being a bit more expensive. We have been late coming back, where they had to hold the boat, at least twice. Had they not held the boat flying to the next port would have been costly, and stressful. It is just not worth it. Also we were robbed by using a non-cruise ship excursion one time when we all the cruise ship excursions were booked. No thank you.

Believe it or not the shopping on ship can be a really good value. I have been considering a GoPro and our recent cruise had a competitive price plus no tax. Buying on ship would have been a better deal then buying in the US.

First time cruisers tend to spend a lot on portraits, but the novelty wears off. We tend to use one of our cruse photos for the next year's Christmas card. Pictures are kind of expensive.

One way a lot of gullible people get sucked in is the free "art auctions". Park West is aboard just about every cruise line and they rob people blind. Don't fall for their marketing tactics. They are experts at getting you emotionally attached to stuff you can buy at Home Goods for $60. They will charge you hundreds for the same art.

The same kind of thing goes on in port. The cruise ship will hold seminars on "ports of call" and offer all kinds of incentives and coupons to visit jewelry shops in port. Most are rip offs. Tanzinite International is a major culprit. Now you can get good deals on luxury watches and such, just do your research ahead of time and understand what a good price is to pay.

Bringing things from home can greatly reduce the price of your cruise such as: sunscreen, aloe, water shoes, snorkel gear, medicines, insulated coffee cup, water bottle, id lanyard, book(s), games, sun hat, sunglasses, shawl (the wifey gets cold easily), backpack, etc...

Really cruises are a great way to have a relaxing vacation. Very little is required of you. This past cruse I had a need to get a small internet package, and that was pretty reasonable.

For the record, I sailed NCL in 2018 and will probably not sail them again. There were many people over served and were very obnoxious. We liked the Cirque du Soleil show on board, and the fact you can make reservations for the various shows. We did do some specialty dining and found the value good. Shore excursions were reasonable. But with the falling down drunk passengers, and the amount of time spent at account services desk the made the vacation less fun than other brands.

Alcohol

Packages vary from line-to-line. Some come with simpler beer packages and some offer wine packages. All have bars and most offer mixed drinks on a per-drink basis.

Premium coffee

While basic coffee is generally free on most lines, expect to pay for Starbucks-like fare (like lattes, etc). Remember to tip your barista!

Rides

Depends on the ship. Royal Carribean's largest ships feature their North Star craned viewing deck. It's a premium ride. Some newer ships (there's a lot of new ones out there) will have premium rides. Most offer slides (wet or dry) for free.

Gambling

Except for Disney, all cruise lines have full-on gambling facilities with the games you expect (slots, blackjack, roulette, etc). You might not consider this a cost, per se, but understand that Disney shocked the industry by not having one. These are major profit centers for the cruise industry. Disney does offer cash-prize bingo, however.

Private Islands

I see you have a food and drink package. Understand that private islands may not be included in that. Expect them to not only hawk merchandise, but to sell you things like chilled bottled water. And while merchandise on the ship is duty-free, private islands must charge you sales tax. Some offer private areas for a fee. Expect plentiful beach rentals.

Tips/Gratuities

You're going to have staff doing things for you. The tips vary from line-to-line, as do the personnel, however your hotel staff does not. Expect to tip these people on a per-day basis. Disney (which has a more defined personnel) has a page breaking their recommended tips down. You'll note the per-person tip goes up the longer you cruise. Disney also "bills" you the tips so you can personally hand slips out. Some packages may have the base tips included.

Travel Insurance

You can always buy your own, but insurance (especially for Latin/Central America cruises during hurricane season) is a profit center. Consider buying your own, or at least price compare before buying a cruise line's insurance.

Spa/Gym/Workouts

Spas are another profit center. You might have access to a workout room for free, but expect to be upsold treatments and services while you're there.

Movies

Not just the theater kind, but potentially in-room as well. Some offer premium setups like IMAX.

Others explained the ways you can end up paying more cash.

You can definitely find ways to cheap out on the cruise. EG: only eat at the free restaurants, tip only what's expected, avoid gambling, avoid video arcades (mostly for kids, b/c they're like $1/play), etc.

But, if it's your first cruise... I would argue to just spend cash like you're James Bond with an expense account.

Wife and I went on a cruise, and I like to vacation like money is no object. This lets us have tons of fun.

• We got to swim with dolphins. Other folks cheaped out and paid less for the "everyone sit in a circle and watch the dolphin" package. Wife and I splurged on the "get in the water and swim with the dolphins" package. There was only 6 of us swim-with-dolphin folks. We had an AMAZING time, the trainers were showing us how they trained them, we were in the water more then out of the water with the dolphins, we got to touch them and ride on them and hug them. We spoke to others that did the cheaper package and they were super envious. It was a lifetime experience I'll never forget, so I don't care how much it cost.

• We gambled ... wife likes to gamble. She did. She won some, lost some. Who cares. She had fun. She doesn't have an addiction. But, it was a fun time to see her gamble and have fun.

• We paid for a pay-for exclusive restaurant. It was a $200+ meal, and totally worth it. Some of the best steak and lobster I've ever had. While the waitstaff in the normal restaurants were as attentive as they could be, at the pay-for restaurant we had our own waiter (one waiter per-table) that waited on us hand-and-foot and made us feel super special. It was an amazing evening. This person knew when to back off and just let us chat and enjoy our drinks, and when to step in and make recommendations on wine, food, joke with us, etc. Amazing experience. Well worth the money.

• Wife played bingo a lot. You pay for the bingo cards. She would play like 6 cards at once or so. She roped me into playing one time. I ended up winning! It was amazing. You might not win, but it's fun.

• We went souvenir shopping when on-land, and got some really nice stuff. We got the usual (a conch shell in carribean), but we also found side vendors that were their own boss. We bought an amazing painting from a street artist doing seascapes with just some paints, fingers and a few brushes. Amazing work. It was inexpensive, but priceless to us, b/c it was a unique, once-in-a-life-time thing we paid for. Well worth the money. We had the artist sign it (he was surprised we wanted him to sign it.. guess most folks don't care about the artist) and have it framed and hanging in our living room to remind us of that trip.

• We did SNUBA diving excusion, which was a blast. We paid for extra long excusion, and got taken out to more reefs and got to dive longer then others. Again, when we talked to folks back on the boat, they were envious and wished they had blown the extra cash to do the top-tier excursion.

• Every time they had a photo op, we took it. You go to a kiosk and choose which pics you want to buy. You don't have to buy any. But, the photographers they used were really good, and the touch-up they did on the photos was good without looking fakey. Wife bought several photos on dress-up nights, and one is our main couples photo we have framed and displayed in our living room as our "this is us" marriage photo. It looks professional.

• I spent about $50 playing a racing game in the video arcade. I'd wake up early in the morning, and would get bored. So, I'd grab some coffee and go play the racing game. I had a blast, and got pretty good.

Cruises have become more common place, so some folks are finding ways to cheap out. But, for others, it's a once-in-a-lifetime trip. If the latter is the case, why cheap out on events? Go explore and splurge and treat yourself. You don't want to get back home and go "darn, wish I paid a bit more to swim with actual dolphins instead of being cheap, and wish I had spent the cash for that souvenir I can't get here."

BLUF: You will have a $15/day service fee at the end. I have heard you can get out of this by filing paperwork. That's it! The rest is up to you. (Ok, for some reason, they charge you taxes on drinks you have while in American ports. Wild, huh?)

I just took my 1st cruise (fyi, I was solo, 7 days) ever on NCL Escape in December 2019 on the cheap in one of the interior studio cabins and with a drink package. As you know, tips for drinks were already included in your prepaid package (~20/day). I tipped RARELY, maybe $1 for quickly served and/or delicious drink. I didn't feel bad or feel pressured ... as I was already giving ~$35/day.

There are certain restaurants (5 on Escape) that cost you nothing. I stuck to those.

I'm not a snobby drinker ... I tried to pace myself mostly w beer.

The ATMs on-board were all mysteriously broken which means you were restricted to using credit cards. This is bad if you want to haggle with the indigenous peoples. I wish I had brought about $1000 in cash. Also, 2nd and 3rd world ATMs dont read cards w chips (I had to call my bank and get them to shut off that feature for 24 hours!) Also, if you want to visit any adult areas, you need cash, jussayin... (I didn't realize when I turned my casino chips in they would give me cash ... fyi, for a 3% fee they do a room charge to your credit card for chips and then I could have cashed them out.)

The entire cruise and corporate islands are a sales trap. I didn't even glance at all that overpriced merch. I went across the street and shopped w the locals .... some took credit.

In the end, felt a little harangued by all the sales advertising/loudspeaker announcements and a bit saddled by the agenda. I did my own thing, mostly, sang karaoke a lot and got to know the regulars in that bar.

It could depends on where you book the cruise. e.g. in Europe you may find more "transparent" costs (and protection), but with higher rates, compared to US travel agencies. Tickets sold (from some countries/ and some cruise lines (on some countries) add separately port fees (and maybe fuel supplements).

The gratuities are the most important hidden fee (but it could be included in the fare), but the recommended amount is written in the FAQs and in various places, so you should know in advance how much you spend.

Drinking: it could be expensive, and gratuity could be added. (Check your cruise line, if you in your drinking package you have mandatory gratuities included, and which drinks are included).

Hidden drinking costs: sometime cruise lines encourage you to buy more expensive drink, or drinks with fancy glasses. If you do not want to collect them, ask for normal glasses. Good coffee could be expensive.

Insurance/medical expenses: this could have a large financial if you do not have them. For sea sickness, ask crew member about tricks, and at guest relation you may get free pills. But for any flu like symptoms: got to medical staff. In any case: you may get in new countries, new foods, but also alcohol and adventure: do not underestimate risk for of having to visit a doctor or to skip pre-paid excursions).

Visa, passports: these fees are not included in the fare. Visas may be mandatory, also if you do not intend to go offshore.

Transfers (and porters): these could be expensive, and they profit of "tourists". A short trip in taxi could be very expensive (and it could be difficult to find honest people near piers).

Money: you go in different countries, so you need different currencies. ATM at ports is the best way. Dollars may not be accepted everywhere (and with not "ideal" changes). WARNING: not all ships run with US dollars as official currency.

Phone and internet are very expensive. Do not trust the "roaming included" packages: I never saw any of these including satellite (maritime) communications. So airplane mode, and check packages and offers. Crew members uses WiFi at ports. Restaurants and bar at ports have free WiFi, but you may need more, so get prepared. [Do updates, downloading "offline maps", translation, etc, before you embark]

Tourist traps: cruise lines bring a lot of tourists (and on a regular basis, and on well know places), so you will find many tourist traps (and very well organized).

Auction: they are well know traps: bad and expensive things. Skip them, ignore the free sparkling wine trap.

Hotel: if you travel with airplane (mainly a long haul): book an extra night before to embark.

There are 4 big expenses that your ticket price doesn’t cover: gratuities, food & drink, at sea days and excursions. The at sea days catch you because you are on the ship all day and will want something to do, other than sitting round the pool almost everything there to do can cost you money.

Gratuities: The recommended gratuity will be automatically added to your bill. You could get this removed but I wouldn't as the staff earn far less than minimum wage.

Drinks: The drinks package will only include "basic" drinks, the branded stuff costs extra. Also even you the adults have the full drinks package watch out for the price of the kids soft drinks, these are very high on some lines.

Food: Each ship has several places to eat, the better ones often have a surcharge. A good tip is to prebook these. Also coffee, ice-cream etc may not be included.

Spa/Gym/Spa treatments: These can add up fast.

Casino: Same risks as any other casino.

Shops/Sales/Auctions: Mostly overpriced, in particular I'd strongly recommend you avoid art and jewellery purchases.

Excursions: Almost always expensive but often worth it. You can get cheaper ones by booking yourself however there are some risks: If you are delayed the ship will not wait. If the stop at that port is cancelled you won't get a refund. Some cruise lines with give priority to people on their excursions when you leave the ship.

Insurance: Can't avoid this one but you can shop around.