A boat has sunk in Coromandel Harbour causing a small amount of diesel to leak into the sea.

Waikato Regional Council staff are now working to stop the leak from the vessel which is moored in the harbour, close to the ferry wharf near Te Kouma.

In the early hours of this morning Coastguard towed the stricken vessel to the Coromandel Harbour and moored it, council's regional on scene commander Dave Lovatt says, after the vessel had broken down close to the harbour.

It subsequently sunk while moored, with no persons on board.


A small amount of diesel had since begun to leak from the fuel tanks of the 10-metre vessel.

"A diver has just arrived at the scene and will be going underwater this afternoon to block the breathers of the fuel tanks to stem the flow of diesel," Mr Lovatt said.

"There's an estimated 200 litres of diesel on board, but at the moment only tiny amounts is escaping into the water. We have our harbourmaster on the scene monitoring the situation and we have booms on standby ready to be deployed if required.

"However, the good news is that the choppy conditions will help to disperse and break up the diesel and minimise any environmental impact," Mr Lovatt says.

As a precaution, iwi and nearby shellfish farmers have been notified of the incident.

The owner is liaising with an Auckland-based salvage company to arrange removal of the sunken vessel from the water, which may take a few days.