An unmanned, submerged boat was found on Lake Macquarie in a busy day for emergency services on the water on September 2.
Lake Macquarie Marine Rescue responded to a call about a sinking vessel at Valentine on Saturday morning.
Crews arrived to find the 8.6 metre boat was submerged. No one was on board.
Transport for NSW said on Sunday afternoon the vessel was semi-submerged, and the owner has tried to refloat the vessel to no avail.
"NSW Maritime is monitoring the situation and liaising with the vessel owner to have it removed as soon as possible," a Transport spokesperson said.
"There are no pollution concerns. NSW Maritime is continuing to investigate the incident."
The marine rescue team was also called to help another boat with a tow at Mannering Park.
"The day had been jam packed with our crews at the Pelican Markets, at our Radio Operations Centre at Swansea Heads and on the water," the rescue team posted on its Facebook page.