A fire on board the Belfast-to-Heysham ferry this morning forced the ship to return to Belfast Port.
The fire started at 8 a.m. in the engine room of the Seacat Rapideferry just over an hour into the sailing to the Lancashire coast.
The fire was "swiftly extinguished" and no one was injured. There were 244 passengers and 20 crew on the ship.
A spokesman for the company said all passengers have been accommodated on alternative carriers and that the company has started an investigation.
"A full internal investigation is under way and there will be an independent investigation by the Marine Accident Investigation Bureau who have been fully informed of the incident," the spokesman said.
The Coastguard said it was not asked to take any action.
The company has cancelled the 5.30 p.m. Belfast-to-Heysham sailing and said it would issue a statement about future services later today.