A six-metre long cruiser is being craned out of Wollongong Harbour after it sunk overnight.
Fire and Rescue NSW were first called out to help on Tuesday after the owner of Gee Tee noticed the boat was taking in water.
FRNSW Inspector Chad Wallace said a submersible pump was fitted to try and pump out the water.
"We did that and then left it for the owner to try and fix the leaks. He obviously wasn't able to do that in time," Inspector Wallace said.
"I believe that overnight the boat started sinking and was three quarters under when we got here today.
FRNSW HAZMAT specialists worked to prevent a potential spillage from the sinking boat for most of the morning.
"We've put booms around the boat to minimise oil and petrol spillage from the boat.
"There is currently no oil or fuel leaking from the vessel," Insp Wallace said.
NSW Water Police were also in attendance.
This was the third boat in as many months that has sunk in the harbour.
We depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support.