It wasn't immediately clear what led to the incident. The U.S. Coast Guard was called in to help find the passenger, but has since called off the search.

A passenger on the Ruby Princess is believed to have gone overboard ahead of the cruise ship’s arrival Monday in San Francisco, according to officials. In a statement, Princess Cruises said the 72-year-old man was not found following an extensive review of closed-circuit television footage and several searches of the vessel.