'Strange Smell' Reported As Mystery Surrounds Woman's Death On Boat

Maritime safety officers are investigating the death of a 39-year-old woman onboard a boat in Sydney, with reports of a "strange smell" onboard.

Australia's maritime safety regulator is investigating possible breaches of national laws, and police will prepare a report for the coroner, after the woman's mysterious death.

Emergency services were called to a marina in Balmain just after 4pm on Saturday after the woman was found unconscious in the bathroom of the Lady Rose, a three-level vessel owned by All Occasion Cruises.

The 39-year-old Berowra woman was treated by paramedics but was unable to be revived. Police said she was found deceased at the scene.

Boats on Sydney harbour in January (AAP Image/Dan Himbrechts)

It's believed the woman collapsed in the bathroom, with a police spokeswoman saying passengers on the boat reported a "strange smell".

The death is not believed to be suspicious or drug-related, police said.

The Sydney Morning Herald on Monday reported that hazardous material teams recorded "extremely hazardous" levels of hydrogen sulphate in the toilet cubicle, however, police and Fire and Rescue NSW were unable to confirm.

"Investigators were advised that several gas detection tests were conducted in a bathroom area of the vessel and were found to be in excess of safe operating levels," police said in a statement.

"The vessel has been secured at the Marine Area Command base where further forensic testing will be completed. A post mortem examination will be conducted to determine the cause of the woman’s death."

The AMSA will also investigate the circumstances leading up to the death.

"AMSA will be investigating whether there have been any breaches of commercial vessel regulations under the Marine Safety (Domestic Commercial Vessels) National Law Act 2012," a spokeswoman said in a statement to AAP on Monday.

All Occasions Cruises has been contacted for comment.

With AAP.