People are being advised to avoid swimming at Jibbon Beach for the next few days after a ship ran aground and leaked fuel.
About 3am on Sunday two people were sleeping on board the 20 metre flybridge motor cruiser, which had been moored at the RMYC Port Hacking, when they woke up to find the boat aground on Jibbon Beach.
The vessel had broken away from its mooring and during the beaching was punctured, took on water and sank. No one was injured.
Roads and Maritime Services and Fire and Rescue were called and placed a boom around the vessel.
It is not considered a pollution hazard.
A salvage company will work to recover the vessel on Wednesday.
It will involve first repairs to the hull at low tide and then refloating at high tide.