Reported sightings of strange creatures in our river go back to colonial times.
Tony Healy, investigator of the unexplained, visited the Hawkesbury in March to find out what locals thought about the long-standing rumours of a 'monster' in the Hawkesbury River.
Mr Healy, a Canberra local, has been roaming the world in search of semi-legendary creatures since the 1970s.
His new 'mission', to find out whether there is truth to local 'monster' sightings, saw him speak with a number of Hawkesbury and Brooklyn locals - some who reported seeing 'monster sized' eels, and others who simply couldn't explain what they saw. Others were skeptical of the mission.
"During my week in and around Brooklyn I encountered a lot of (understandable) skepticism about the 'monster', but also heard quite a few interesting eyewitness reports of large, frightening animals that might, or might not, have been the creature in question," Mr Healy told the Gazette.
"As yet, I certainly don't feel qualified to make a call on whether the critters really exist, although there's reason for cautious optimism."
Mr Healy began his trip by checking in to The Anglers Rest at Brooklyn, the publican of which had never heard of the 'monster'. Many locals down there were skeptical of any 'eyewitness' reports, claiming anyone who said they'd seen anything was telling tall tales.
"Loggerhead turtles were occasionally mentioned. With their large, humped backs, long necks and reptilian heads, those occasional visitors to the Hawkesbury might appear somewhat plesiosaur-like in silhouette," Mr Healy said.
"But the animals mentioned most often as candidates for misidentification were eels - huge eels."
Mr Healy said there are several species of eel in the Hawkesbury, and the Australian longfin (AKA the brown spotted eel, the speckled longfin or the marbled eel) is one of the most common. While females are known to grow to 1.6 metres, there have been unconfirmed reports of them growing up to 3 metres in 'landlocked' areas, he said.
One eyewitness Mr Healy spoke to was Dan Selby of Sydney Sports Fishing Adventures, who in 2003 was canoeing near North Richmond, and "drifted alongside a 'log' in the weeds, and then realised it was the carcass of an eel. It was 40 centimetres [15 inches] across."
Although some of its girth might have been due to bloating, Dan could see the entire body, head-to-tail, which was "as long as my canoe: three metres," he said.
'M' of Sackville once saw, from The Terrace at Windsor, "a brown spotted eel just under the surface, about ten metres from the opposite bank. It was doing 'figure eights': just chasing its own tail.
"We could judge its size because there was a cow grazing on the far bank, and even in the 'figure 8' configuration, it was longer than the cow - so I estimated its length at four metres [13 feet] and its girth at 12 inches [30.5 cm]."
Then there were the people who simply couldn't explain what they saw. Two men told Mr Healy about "strange animals at Mooney Mooney" - two separate, yet similar, accounts.
The first account was from Martin Shaw, who in 1999 or 2000, saw a very strange-looking animal, that at first he thought was a log, surfacing repeatedly.
From a rock 100 metres away, he estimated the animal was around the same size as a seven-metre boat he owned.
"It surfaced repeatedly, loafing around, and articulated around the centre, like a semi-trailer - slowly bending back and forth. I saw it pretty clearly. There was no sign of dorsal fins, etc. I estimate it was up to one metre [broad] at either end, but narrowed towards the centre to about half that," Mr Shaw told Mr Healy.
A similar sighting by 'A. M.' occurred in 1995 when he was 12 years old. From 100 to 150 metres away, he saw an animal about 20 feet long, just above the water, which appeared similar to a crocodile. He said it moved stealthily and quickly.
A more dramatic report came from 'M', who was fishing in Sackville in 2005, when he saw a great pressure wave indicating something very large was under the water, causing a 10-inch high double wave to come towards him.
"It had rounded up a big school of mullet, and they were jumping out of the water, dozens of them, trying to get away," 'M' told Mr Healy.
Mr Healy also heard various second-hand reports of plesiosaur-like animals - similar to common depictions of the Loch Ness 'monster' - being seen at Wisemans Ferry.
"The information I collected at Brooklyn was intriguing enough for me to plan a second expedition," Mr Healy said.
He plans to return to the Hawkesbury River in August to continue his mission between Windsor and Spencer.
Mr Healy said he will publish the results of this and other expeditions in a memoir he has been working on. The working title for the book is Monster Safari.
Anyone who'd like to share relevant information can contact Tony Healy on 0410 039 689 or at firstname.lastname@example.org.