Rescuers were not alerted to the disappearance of a cruise ship entertainer until he failed to report for work, nearly 10 hours after he is believed to have gone missing.
The last CCTV footage available of Arron Hough, 20, showed him heading on to the Royal Caribbean ship’s deck at around 4am, according to a statement issued by the company.
However, staff on board the ship only realised he was missing when he did not report to work later that day, the statement added.
The United States Coast Guard was alerted to Mr Hough’s disappearance at 1.45pm, a spokesman said.
The vessel, named Harmony Of The Seas, was 267 miles (430km) north-west of Aguadilla, Puerto Rico, at the time and was travelling to Philipsburg, St Maarten.
The United States Coast Guard said it had deployed a Clearwater HC-130 Hercules aircraft crew and the Coast Guard Cutter Resolute in the search.
A spokesman for Royal Caribbean said: “We are saddened to report that, after a review of the ship’s closed-circuit camera footage, he was observed entering an area on Deck 5 at around 4am and was not seen again.
“Local authorities were notified and a ship-wide search for the crew member was conducted.
“Our care team is providing support to the family and friends of our colleague, and our thoughts and prayers are with them during this difficult time.”
Royal Caribbean and the United States Coast Guard were unable to confirm how far the ship travelled during this time.
Mr Hough is from Sunderland and attended the London-based drama school Urdang Academy, according to his Facebook page.
The academy is “praying” for Mr Hough and his family, according to a message posted on Twitter.
It added: “Please keep up your hope and faith that he is found safe and sound as soon as possible.”
In July, talent agency Russell Smith Associates tweeted that Mr Hough would be joining the cast of Grease The Musical on Harmony Of The Seas.
The London-based agency said: “Our thoughts are with all of his friends and family and we hope for him to be found very soon.”
The Royal Caribbean website says Harmony Of The Seas won the title of largest cruise ship in the world in 2016.
The ship cost one billion US dollars (£695 million), can carry 6,780 guests and 2,100 crew, and took more than two-and-a-half years to construct.
The website says it is the first ship to feature the Broadway hit musical Grease as part of its entertainment programme.
Harmony Of The Seas departed from Fort Lauderdale, Florida, on Sunday for a seven-night cruise including calls at Philipsburg, St Maarten, San Juan, Puerto Rico and Labadee, Haiti.