Though vacation is about relaxing and taking a break from your everyday life, it's important to remember that you're sharing the cruise ship with thousands of other guests. As such, there are specific rules cruise passengers must follow to help maintain a safe and positive environment.
Breaking the rules can have serious consequences, ranging from hefty fines to a permanent ban from the cruise line.
Ultimately, good manners are about treating others as we’d like to be treated. You wouldn't want someone coming into your home and stealing or acting recklessly, and the same applies to a cruise cabin.
Here are 6 things you should never, ever do in your cabin.
Smoke or vape

Cruise ships have certain areas where smoking is permitted. Cabins, however, aren't on that list, even if you think it's okay because you have an outdoor balcony.
On embarkation day, familiarize yourself with the ship's smoking areas. They might be inside the casino or near the pool deck.
If caught smoking elsewhere, you face being billed a hefty cleaning fee. Onboard Carnival ships, for instance, the fee is $500, whereas Royal Caribbean only charges $250. Still, you don't want to be charged for something completely avoidable.
Read more: Can you bring a vape on a cruise ship?
Throw things overboard

Don't throw anything off your balcony into the ocean. Cruise ships have strict rules about throwing things overboard, as companies strive to protect the marine environments they operate in.
Even if you have good intentions, like feeding the fish, doing so can harm the delicate ecosystem. Food scraps, for example, can attract invasive species and disrupt local wildlife behavior.
Non-biodegradable items are even worse. Plastic straws and cigarette buds can cause lasting damage to habitats, as they're often mistaken for food. Ingesting the plastic can cause death.

Similarly, just as cruise lines don't want you throwing anything overboard, they don't want you to take things from the ocean, either.
That's right: someone has actually gotten banned for fishing off their stateroom balcony on a Carnival cruise. They shared a clip of their actions on social media, which is how Carnival executives caught wind of the incident.
Flush random things down the toilet

Cruise ship plumbing is more sensitive than your toilets at home. Things like feminine products, diapers, and even "flushable wipes" can quickly clog the system and cause serious plumbing issues in your cabin and elsewhere onboard.
Instead, only flush the cruise line-provided toilet paper. Everything else should go in the trash can in your bathroom to be cleared at least once per day by your cabin steward.
Likely, the toilet paper isn't as plush as your preferred brand back home, but that's intentional. The thinner, marine-safe toilet paper quickly breaks down and prevents clogs. In other words, do not bring your own toilet paper to use. If you do, it needs to go in the trash bin.
Climb on the balcony's railing

From sunset pictures on the pool deck to elegant formal night pictures in the atrium, cruise ships offer many picture-worthy (and safe) photo ops. Though ship photographers aren't cheap, it's easy to snap lasting memories with your cellular device.
While personal balconies also make for great backdrops with minimal activity in the background, there are certain poses to avoid. For example, you shouldn't climb on your balcony's railing for a daring angle.
If caught, you may be banned from sailing with the cruise line again. In 2019, for instance, CNN reported about an incident that led to a woman being prohibited from sailing with Royal Caribbean again.

While she thought she was getting an epic selfie on Allure of the Seas, security was notified about her reckless and dangerous pose. Consequently, she and her companion are banned from cruising with Royal Caribbean.
Read more: 10 Reasons You Could Get Banned From A Cruise Ship
Steal

As comfortable as your cabin's pillows might be, you don't want to smuggle them off. That goes for everything owned by the cruise line in your stateroom, ranging from robes and slippers (if provided) to towels, hangers, and decorative wall art.
You will likely be charged for anything you take, as cabin stewards assess the staterooms for stolen property on turnaround day.
Certain cruise lines, namely Royal Caribbean, also charge for pool towels that aren't returned before leaving the ship. This means that even if you think you're safe because you left them in your cabin, you may find a $25 fee charged to your onboard account for not returning them to the proper place.

That said, many lines sell their signature items through special websites. For example, you can purchase Royal Caribbean's bedding online. Similarly, Carnival Cruise Line sells their towels, bedding, pillows, and robes at carnivalhome.com.
Leave your balcony door open

Finally, always ensure your verandah door is securely closed before opening the door to the hallway.
If both are open simultaneously, it will create a strong wind tunnel that can be potentially dangerous and blow around papers, clothing, and other items.
Plus, keeping your balcony door closed helps your stateroom remain cooler, as the air conditioning will remain inside, rather than escape outdoors.
Read more: Balcony cruise ship rooms: are they worth the splurge?