Around 2am, emergency services were called to York Street, following reports of an explosion.

Police from Lake Macquarie Local Area Command attended the scene, where they found a boat on fire.

The vessel, a Mariner 780 cruiser, had also been cut adrift from the wharf where it had been docked.

Personnel from Fire and Rescue NSW extinguished the blaze.

The fire has been deemed suspicious and officers are appealing for anyone with information of relevance to come forward.