While cruise ships may seem like a vacation paradise, you'll find the seven deadly sins running rampant onboard -- from greedy chair hoggers to wrathful malcontents ready to yell at the first crew member that gets in their way.

Cruise Critic takes a look at the seven deadly sins of cruising to tell you which cruisers to watch out for -- and how you can take the saintlier road toward being a more respectful, happier and healthier vacationer.

1. Greed

The Sin: You're a lucky (and rare!) cruiser if you haven't encountered some of the most notorious -- and greedy -- cruisers sailing on the high seas: the chair hoggers. These folks feel entitled to as many chairs as they want, whether on the pool deck, in the ship's most comfortable lounge or in the theater, where they're saving numerous prime location seats despite the clearly communicated "no saving seats" rule. Their greedy behavior prevents other passengers from finding a lounge chair near the pool or a good view of the stage.

Be a Saint: Rise above your greedy inclinations and share the cruise ship's bounty with your shipmates. Take only the chairs you plan to use right now, and let others take the available seats next to you. Who knows? You might strike up a conversation with the strangers seated beside you, find out you have much in common and become fast friends, enhancing your vacation experience.

Gluttony (Image: Lightspring/Shutterstock)

2. Gluttony

The Sin: Another of cruising's most visible sins, gluttony is often in full force in a cruise ship buffet, which never runs out of food (unless you show up 10 minutes before closing). Cruisers routinely heap piles of food on their plates, as if they have to hoard rations for the weeklong sailing. Sure, the food is free (well, included in your cruise fare), but do you need to overindulge? The next meal is always just around the corner.

Be a Saint: Eat like you would at home, filling a plate with an entree and a few sides and taking just one dessert. If you're too tempted at the buffet to take yet another piece of bacon or feel compelled to try all the desserts, consider eating more meals at sit-down restaurants where you can order off a menu instead of seeing all the food in front of you.

3. Pride

The Sin: Prideful cruisers make the most annoying fellow passengers. We've all met the guy who's been everywhere and can one up your travel story every time, the women who got the best price for the cruise and can't believe you paid "how much?!" and the couple who can't stop talking about how much better their suite is than your room. These are the cruisers who believe they're superior to you and make sure you know it.

Be a Saint: It's fine to swap stories with your shipmates, but there's no need to brag. If you're about to say something that might make your new pal feel bad about their vacation, bite your tongue rather than ruin someone's day. If you need to boast, do it in the privacy of your cabin with your travel partner.

4. Envy

The Sin: Cruise ships are full of inequality, and those who succumb to envy of their fellow passengers are bound to have a bad time. It's bad enough that they moan to their travel companion about the cruise passengers who are prettier, more fit, better dressed, richer and enjoying larger suites and nicer perks. But trying to slip into the theater section reserved for suite passengers, complaining about Diamond-level loyalty passengers jumping the tender queue or "borrowing" the flotation devices that come with high-priced cabana rentals is simply rude and immature.

Be a Saint: The grass will always be greener in the suites-only lounge and sun deck, so forget about everyone else's cruise experience and focus on enjoying your own. Even in the lowliest cabin, you can still eat fancy food, enjoy the ocean breeze, watch a show and get to shore. When envy has you turning green, just post a vacation photo on social media -- and watch all your friends at home become jealous of you. It might help to give you perspective.

Lust (Photo: Fabrik Bilder/Shutterstock)

5. Lust

The Sin: Everyone's favorite deadly sin, lust is also one of the most inconsiderate sins on a cruise ship. No one wants to see excessive public displays of affection or hear their neighbors' bedroom antics through the thin cabin walls. The bridge crew would rather not spot yet another couple having sex on the balcony (and yes, they can see you!).

Be a Saint: All you have to do is be respectful. Keep your romantic escapades to the confines of your cabin (and consider turning on some music to muffle the noise). Don't be the guy who catcalls at the women in bikinis or the dude creeping up on every single lady in the dance club. And leave the crew alone; they have strict rules against cavorting with the passengers, so don't try to get them in trouble.

6. Wrath

The Sin: Wrathful cruisers find fault with everything, nitpicking at every meal, complaining about every drink, every activity, every show. They're the folks who demand to speak to the cruise director about the comedian's tasteless jokes or the hotel director because their room steward didn't make them a towel monkey. But the worst of this bunch are the yellers, the passengers who raise their voices to and belittle the crew. That is the cruise sin we find to be the most unforgiveable.

Be a Saint: Remember you're on a relaxing vacation; you can afford to be Zen about a mediocre entree or a less-than-stellar guest performer. If there is a larger issue you need to raise, state your grievances in a calm, mature fashion, and keep in mind that the ship's crew is doing their best to solve any problems that arise and genuinely want you to enjoy your cruise.
Sloth (Photo: Nelli Syrotynska/Shutterstock)

7. Sloth

The Sin: Sloth is the most forgivable cruise sin. After all, cruises are designed for being lazy and lying about all day long. But the worst of the slothful bunch are those who make life more difficult for others with their laziness -- from the cruisers who think its OK to leave their cabins an absolute mess, expecting their room stewards to clean up for them, to the passengers who neglect to wash their hands and spread germs around the ship.

Be a Saint: You don't have to go to work, cook or run errands on a cruise, so you can spare a few minutes to pick your dirty underwear off the floor or remove that wad of hair from the shower. And for Pete's sake, take 20 seconds to wash your hands after using the bathroom and before you eat, to keep norovirus and other nasty bugs at bay.