Authorities were conducting an air and marine search Thursday off Australia's east coast for two cruise passengers who were believed to have fallen overboard the night before.
The couple, Australian citizens from New South Wales state, were discovered missing Thursday morning after the Carnival Spirit docked at Sydney's Circular Quay, at the end of a 10-day journey, said New South Wales Police Superintendent Mark Hutchings.
He said surveillance camera footage showed that the couple – a 30-year-old man and a 26-year-old woman whose names have not been released – fell from the ship's mid deck Wednesday night, when the ship was about 65 nautical miles off the coast of Forster, a city 185 miles north of Sydney.
"This is a tragic event at the moment, but we're holding out hope we might be able to find these people alive," Hutchings told reporters.
Investigators were having the video enhanced in a bid to determine whether the couple had jumped or had fallen by accident, Hutchings said.
The ship has around 600 surveillance cameras that are constantly monitored, although no one reported seeing the fall at the time.
No life preservers were missing from the ship, Hutchings said. A missing life preserver might have indicated that one of the missing passengers had attempted a rescue.
The couple and seven of their family and friends were among 2,680 passengers on a South Pacific cruise. The ship's last stop was Mare Island in New Caledonia, which it left on Monday, bound for Sydney. The couple were discovered missing as passengers disembarked, said Peter Taylor, spokesman for the ship's operator, Carnival Cruise Lines.
Carnival Corp. has been plagued by a series of high-profile problems in recent years. Last year, the Costa Concordia ran aground off the coast of Italy, killing 32 people. Also last year, the Costa Allegra caught fire and lost power in the Indian Ocean, leaving passengers without working toilets, running water or air conditioning for three days. Costa is a division of Carnival Corp.
In February, passengers aboard the Carnival Triumph spent five days without power in the Gulf of Mexico after an engine-room fire disabled the vessel. Those on board complained of squalid conditions, including overflowing toilets and food shortages.