Royal Caribbean International said 243 of 3,252 passengers on board the Explorer of the Seas had caught a norovirus, a common cause of infectious gastroenteritis prevalent in hospitals, nursing homes, cruise ships and other semi-enclosed environments. All those affected were treated.
Nineteen of the 1,184 crew members also took ill during the voyage, which made stops in Belize, Mexico's Yucatan and the Cayman Islands.
The ship returned to Miami on Sunday.
Royal Caribbean said it believed a passenger brought the virus on board.
