A cruise ship on its way to Australia is now the subject of a frantic investigation as the search continues for a couple who went missing overnight.

The Carnival Spirit had just reached the end of a 10-day trip and had docked at Sydney’s Circular Quay when it was discovered that a couple weren’t on board. A check of surveillance cameras showed that the Australian couple went overboard on Wednesday night, about 65 miles off the coast of Forster. Authorities are now trying to determine whether the man and woman fell or if they jumped, and an exhaustive search of the waters is underway.

“This is a tragic event at the moment, but we’re holding out hope we might be able to find these people alive,” said New South Wales Police Superintendent Mark Hutchings.

A spokesman for the cruise line said immediate action was taken once the couple was discovered missing; they were traveling with seven other people in their party.

“The guests in question were traveling with family and friends, and initial reports indicate that the couple was last seen onboard the vessel last night,” Peter Taylor said in a statement. “The ship immediately initiated standard missing person procedures, including a full search of the vessel, as per protocol,” he said.

This is the latest in a string of bizarre news stories involving Carnival cruise ships; earlier this year, thousands of passengers endured a long week aboard a vessel that broke down after a fire and had to be towed to port; last month, the same ship had to be evacuated after two fuel barges exploded nearby.