A cruise in a liner officially named this summer by the Duchess of Cambridge has had to be curtailed after the vessel lost power.
And the next voyage of the ship - the Royal Princess - is now in doubt.
The Duchess named the ship, part of the Princess Cruises fleet, in a ceremony at Southampton in June - one of her last engagements before the birth of her son George the following month.
Passengers will be taken to Naples for flights home and the ship will leave on Wednesday for Barcelona with only crew on board.
The Royal Princess is due to embark on a 30-day cruise on Friday, finishing in Fort Lauderdale, Florida.
A spokeswoman for Princess Cruises said: "We sincerely regret this means the remainder of the current cruise will be cancelled, and passengers will disembark the ship in Naples.
"Passengers will be provided a full refund of their cruise fare, along with a 25% future cruise credit.
"We have dispatched a care team to Naples to ensure that all our passengers are provided with any assistance they may require.
"The impact of the repairs on the next Royal Princess cruise, scheduled to depart from Barcelona on September 27, is not yet known and we will keep passengers fully advised as details become known."