A norovirus outbreak on a Royal Caribbean ship (NYSE:RCL) has led to more than 270 passengers falling ill during what was supposed to be a vacation cruise through the Caribbean.

The ship in question is the company’s Oasis of the Seas, which is making a return to Port Canaveral a day early due to a norovirus outbreak that led to roughly 277 guests and crew members being affected by the illness as the ship sailed to Jamaica. Passengers are being offered full refunds as a result.

Officials with Royal Caribbean said on Wednesday that there were at least 167 cases of a stomach virus on board the Oasis of the Seas. The company then said on Thursday that this figure had increased to 277.

Norovirus is a stomach virus that causes diarrhea, nausea, vomiting and stomach pain. It can be caused by having direct contact with an infected person, consuming water or food that was contaminated or touching contaminated surfaces and touching your mouth with your unwashed hands afterwards.

Passengers went on social media on Wednesday to express their displeasure over being forced to stay on the cruise ship after docking in Falmouth, Jamaica for a day of excursions. Royal Caribbean said that the decision to return a day early gives the company “more time to completely clean and sanitize the ship” before it ships out again.