Cruise ship workers reveal the 7 most annoying things passengers do

"When they don't wash their hands after going to the toilet, or grabbing food directly from the buffet with their hands," a Royal Caribbean Cruises employee said.

Read more: Cruise-ship workers reveal the most disappointing things about their job

A former chef for Carnival Cruise Line and Royal Caribbean said failing to listen during safety drills was the most annoying thing passengers did.

"Younger [passengers] usually take food and beverages to their cabins, leaving a trail of crumbs and debris along the way," said Aida Carvahlo, a former human-resources manager for MSC Cruises, Viking Cruises, and Holland America Line. "After eating, they leave plates and glasses through the hallways of cabins. Housekeeping staff sometimes find rotten food under beds."

"They behave in a way they would never do at home," said a Royal Caribbean first officer. "Like would you ever call 911 if the internet does not work or your toilet does not flush?"

Going to the dining room right before it closes is the most annoying passenger behavior, said a hostess for Carnival.

A former waitress for Carnival said she was annoyed when passengers asked her questions they could easily find the answer to somewhere else, like guest services or an app on their phone.

"I lost valuable time and money, since my income was based on my sales," she said.