More than 250 people aboard a cruise ship fell ill with a stomach virus while touring the western Caribbean (search), cruise line officials said Saturday.

About 233 of the 3,465 passengers aboard the Mariner of the Seas (search) became sick after the vessel left Port Canaveral on Jan. 16 for a seven-day cruise through the western Caribbean. The ship was expected to return early Sunday.

Twenty of the vessel's 1,190 crew members also showed symptoms.

Michael Sheehan, a spokesman for Royal Caribbean International (search), described the illness as "your typical 24-hour stomach virus and nothing more" and blamed a sick passenger for bringing it on board.

The Mariner of the Seas was also being checked for bacteria, the company said.

Passenger Crystal Wiles, an accountant from Frederick, Md., said in a phone interview from the vessel that she and her husband had been quarantined for three days. She criticized the cruise line's handling of the illness and said the company was undercounting the number of people affected by the virus.

"The treatment has been horrible," Wiles said.