Sixty-six passengers and 17 crew members on the "Crown Princess" are believed to have come down with the highly contagious norovirus while the boat was docked in San Francisco Monday, Princess Cruises spokeswoman Karen Candy said.
The norovirus, which has been a recurring problem for the cruise industry, is spread person-to-person and causes flu-like symptoms including nausea, vomiting, diarrhea and stomach cramping.
The Princess Cruises staff is disinfecting the vessel and the sick passengers are being told to stay in their cabins, Candy said.
The ship is on a seven-day cruise and was expected to dock in Santa Barbara Wednesday.
The Associated Press contributed to this report.