"The biggest health concern being on a cruise ship is that of infectious diseases," said Dr. Steven Zell, University of Nevada professor of medicine.
Zell says stomach illnesses like Norovirus are the most likely.
"It's easily transmitted," Zell said. "It's hard to kill outside the body with antiseptics. It can go through a large community in a very short period of time."
So if you're going on a cruise, Zell says to pack a wellness kit.
"That might include like a face mask, disposable latex gloves, hand sanitizers," Zell said.
Just like on land, washing your hands frequently while at sea is the easiest way to avoid catching a bug.
But if you do get sick Zell suggests some self-care tips.
"The most important thing is to hydrate yourself well, to rest, elevate your legs to keep your blood pressure up," Zell said. "You might want to follow a brat diet. That's banana, rice, applesauce and toast."
Zell says the threat isn't limited to flu season, so take precautions year round.
Zell also says it's important to make sure there aren't any required vaccines in places where your cruise will stop. So if you're headed out of the country, you'll want to check with the Centers for Disease Control in advance.