I’ve spent over 100 days at sea. Please don’t make these 6 etiquette mistakes on your next cruise.

Most cruises have buffets, which can be a hot spot for onboard etiquette crimes.

First of all, you should not pick up food, like tortillas or rolls, from the buffet using your bare hands. Instead, use the provided serving utensils or ask the crew for assistance.

I’ve also seen people biting their nails or putting their fingers in their mouths before touching serving utensils, which isn’t sanitary either.

Please wash your hands before hitting the buffet (and after, too).

I’ve found it’s not uncommon to see children running around unsupervised at all hours of the day and night while at sea, particularly on cruise lines that are popular with children.

This can be annoying to fellow cruisers and pretty dangerous. Plus, it can often be easily avoided — most cruise lines have supervised children’s clubs and activities.

On a recent cruise, I was surprised to witness a woman clipping her toenails next to the pool and a man shaving his beard in the spa waiting room.

It felt unsanitary, and it’s also not very polite to leave an extra mess for the crew to clean up. If an activity involves leaving parts of your DNA on the floor, you probably shouldn’t be doing it in a public space.

Your beach towel shouldn’t be laid on the lounger hours before you show up to the pool.

In fact, most cruise lines have policies against reserving deck chairs and seats at popular performances. Don’t be that person who doesn’t adhere to the first-come, first-served process for claiming seats.

Most cruise ships have a fitness center, and being at sea doesn’t mean you should forget proper gym etiquette.

I’ve seen many bad behaviors in gyms at sea, including listening to music without headphones on.

One of the worst ones, though, is when people throw weights on the floor. It’s loud, dangerous, and especially rude to anyone staying in a room below the gym.

(I don’t recommend booking a cruise cabin below a fitness center for this very reason.)

Being rude is never OK, especially not on a cruise ship.

Many cruise-ship employees work seven days a week and more than eight hours a day for the duration of their contracts, which can last for months.

The last thing they need to deal with is your rudeness.