The crocodiles who call the murky depths of north Queensland's Proserpine River home harbour myriad secrets.
The larger-than-average crocs are considered an anomaly, with more large crocodiles per kilometre than any other system in Queensland.
But despite their territorial nature, researchers are baffled at the relative lack of scars and scratches on the reptiles, which they say is usually standard in high-density areas due to fights.
And even more puzzling is why the larger males aren't pushing their competitors out into nearby Airlie Beach, one of Queensland's greatest tourist meccas.
Jurassic Park and paradise
Department of Environment and Science program coordinator Matt Brien led a team of researchers to uncover the "where's and why's" of this intriguing cohort of reptiles.
"It really is as close to being in Jurassic Park than anything else," Dr Brien said.
"There's such high crocodiles in high densities … and they are just around the corner from Airlie Beach."
Dr Brien said the Proserpine River was one of the most significant rivers in Queensland as far as crocodiles and crocodile conservation was concerned.
"Not only does it have the highest density of crocodiles in Queensland, it has the highest density of large crocodiles," he said.
"If you want to see big crocodiles in Queensland, go to the Proserpine River."
He said the river was a "real anomaly", not only because of the density but also because it was relatively far south and was such a small system.
"Usually when we do this crocodile work, we're up the Cape [York], in the dust, in the heat in fairly remote areas," he said.
"So it really is a bit of a strange feeling for us and very unusual to be coming to the Proserpine and doing croc work, and then heading back to Airlie Beach — they're really parallel universes."
Rangers as croc catchers
Recently, the team baited and trapped four crocodiles in a week, ranging in length from 3.9 metres to 4.3 metres.
Cameras were set up outside the traps, alerting the rangers to when they had been successful.
Battling the tides and sun, the rangers headed out early the following morning to scramble the banks, where they were able to carefully sedate the crocodile and attach the tracking device.
Once the operation is complete, they turn the croc towards the river and release it back into the wild.
The river's locals
Tour guide Mark Norman has spent more than two decades on the Proserpine River and knows the system like the back of his hand.
Cruising along the river, he pointed out some of the fan favourites.
"This is Boofhead's territory. He's a big croc. He's been here for a long, long time," Mr Norman said.
"He's probably about 4.4 [metres long], maybe bigger."
Mr Norman was initially sceptical of the tracking program, as he was worried about the consequences of human interference with the crocodiles.
But he says he is excited to find out more about the ancient reptiles that inhabit the river.
"The Proserpine River is quite a unique system in the way the territories operate up here and the way crocodiles associate in such close quarters," Mr Norman said.
"It's a good bit of research to get done."
Solving the mystery
Mackay senior wildlife officer Jane Burns says the project was a huge success.
"We would have been happy with even three animals tagged and we were lucky enough to get four in the end." Ms Burns said.
After treacherous field work, the team is now able to monitor the ancient reptiles from the comfort of their office.
"We do get an update every 24 hours," Ms Burns said.
"So it is quite exciting each day to be able to log back in and have a look at what they're actually doing."
She says the public will be able to access information about the crocodiles' movements from early next year.
The trackers will monitor the crocodiles for another 18 months, with researchers hoping to uncover more of the reptiles' behaviours.
