A luxury superyacht has sunk and others have been destroyed after a huge blaze ripped through an exclusive Sydney marina, causing millions of dollars of damage.

Forty firefighters battled to put out flames engulfing numerous luxury vessels docked at the Spit Bridge marina at Mosman.

Thick black smoke rose over the prestigious boating facility on Sydney’s north shore as the inferno spread early on Friday morning.

The fire reportedly consumed four yachts, estimated to be worth millions of dollars.

Channel Seven reported that one of the superyachts had sunk and three others were destroyed and were starting to sink.

NSW Fire and Rescue said four people were assessed by NSW Ambulance paramedics for smoke inhalation after managing to escape the blaze.

The incident was reported just before 3:30am on Friday (AEDT).

Despite the efforts of firefighters, the flames continued to spread.

The Spit is touted as one of Sydney Harbour’s most prestigious boating precincts with luxury berthing—including dedicated superyacht berths—24/7 fuel, and world-class marina facilities.

Adam Dewberry, from NSW Fire and Rescue, told 7News the cause of the fire would be investigated.

He praised the work of firefighters and said the damage could have been much worse.

“Our main effort now is we’ve got the fire contained, but now we’ve got to look at containing all the oils and fuels off these boats.

“And that’s where we’re putting booms around it now with the Port Authority to contain that contamination for the harbour.

“Our hazardous materials teams, the Port Authority are here on scene. We’ll have that contained quickly.”

He said the recovery effort, involving salvage crews, would take some time.