From dancing to dining to diving, cruises offer an array of ways to keep busy and make the most of a much-needed vacation. That said, there are a number of things you should never do on a cruise — and we don't just mean the obvious bad ideas like skipping sunscreen or boozing too much before developing your sea legs. Here are five major no-nos when it comes to making the most of your cruise.

Skip Your Muster Drill

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Even if you're a seasoned cruiser, the muster drill (where you learn what to do in case of an emergency on the ship) is a must for everyone, and there are serious consequences to skipping out on it. Passengers have been booted from ships entirely for not attending, so suck it up for 20 minutes and do your due diligence.

Book Excursions on the Ship

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We get it: You're on vacation. You want to relax. The problem is, not planning ahead of time can cause you to miss out on some seriously amazing experiences. Briana and Kyle of Married With Maps warn, "Although it may be tempting to go with the flow and book on a whim, all the good excursions will be sold out in advance and the only options left will be lousy or very expensive, or maybe even nothing at all."

Of course, that doesn't mean you have to micromanage a minute-by-minute itinerary for your trip — just make sure that if there's an excursion you're dying to take that you book it before you board.

While your cruise likely offers some incredible excursion options at port, Angela Rice, co-founder of Boutique Travel Advisors, says you have more choices than you realize. "There are highly regarded tour operators around the globe who specialize in offering authentic small group and private port excursions," Rice told Cruise On. "The benefits to private excursions is that you have control over how you to enjoy your time on land while cruising. The port excursions offered by the cruise line are often crowded and require more logistical time (which means less time for you to enjoy the port city or town)."

Rice notes that cruise excursions can also be more expensive than other local options. Researching your options ahead of time, either on your own or with an advisor, can help you customize your excursions and make the most of your time and money while at port.

Mention Too Loudly That You're Not Feeling Well

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There are few things worse than being sick on vacation, and one of those things is being quarantined on a cruise. Cruise Finder, Inc. president Kyle Bruening warns that if you're feeling even just slightly under the weather, keep quiet about it. "Don't broadcast your symptoms to others," he advises. "Doing so could get you sent to quarantine — regardless of whether or not your condition warrants being there. Cruise companies err on the side of extreme caution when it comes to germs, so only visit the cruise ship doctor if you truly feel like you have an issue you can't solve yourself."

Bruening recommends packing a supply of over-the-counter treatments (think Advil, Benadryl, Dramamine, Pepto-Bismol, lozenges, etc.) in case you need them.

Hog the Deck Chairs and Dinner Reservations

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Anyone who has been on a cruise has witnessed That Guy. That Guy wakes up early, tosses a book, a towel and a T-shirt on a deck lounger, and then goes back to bed, ensuring that he has a piece of prime real estate. That Guy also makes reservations at every single one of the ship's swanky eateries for the same night, then decides where he wants to go. Everyone hates That Guy, because That Guy is selfish, greedy and inconsiderate of his fellow travelers.

Skip Exploring All the Ship Has to Offer

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From rock walls to nightclubs to bingo, make sure to make the most of your time on the boat. Charles McCool of McCool Travel says, "Assuming I do not hurt myself or fall off, my biggest regret is when I do not explore all of the activities and features of a ship. Some people may prefer to lie by the pool, sit at the bar, watch comedy shows and eat eat eat, but I like  to explore all that my floating home offers."

Andrew Garnett of Special Needs at Sea advises, "Don’t be afraid to do things you wouldn’t normally do. Have fun and perform at talent night. Participate in the scavenger hunt. Sing karaoke. Chances are, you will never see any of the other cruisers again, so remember to have fun!"

This also includes the myriad dining options ships offer. Sample each of the eateries when you get a chance. Worried about crowds? Try breakfast, when a lot of fellow cruisers may still be snoozing off last night's festivities.

One area to not go too crazy in? The casino. Gambling on a cruise ship is, well, a gamble, especially if you do it on your first night at sea. Will Hatton of The Broke Backpacker offers a cautionary tale. "Don't bet away all your money on the first few days of the trip. I've seen someone lose all their 'spending' money in roulette, and spent the rest of the cruise eating their already paid for set meals and drinking water only, as the drinks were extra," he recalled. "They were also stuck on board when docking in ports, as had to money spend offshore!"