Northern Ireland Fire & Rescue Service (NIFRS) Group Commander Barry Ross said the fire was in the engine room of a tug boat secured on a jetty.
“Approximately 43 firefighters attended the scene, three appliances – one from Carnlough and two from Larne, a specialist Marine Response Team from Whitla Fire Station, the Specialist Rescue Team from Central Fire Station and a Command Unit from Kilrea were in attendance.
“The Coastguard attended with two lifeboats to assist with the resolution of the incident.
“Firefighters wearing breathing apparatus were committed to confirm the fire onboard was extinguished and to ventilate to ensure safety of the vessel.
“The cause of the fire has been determined as accidental ignition,” he said.
The incident was resolved at 7.40pm.