Although Gary Lindner has spent more than three decades keeping an eye on live crocodiles, some of his earliest interactions were with dead ones.

Like him, his father was a wildlife ranger in Kakadu and he was known to bring home the carcasses of crocodiles encountered in the field.

"As kids when he wasn't around we'd constantly open the freezer to look at this crocodile," Mr Lindner said

His fascination with the ancient, deadly reptiles has grown ever since, and Mr Lindner is today the crocodile manager at Kakadu National Park — a patch that includes one of the world's most notorious croc-inhabited waterways.

As Mr Lindner drives to the crossing, he points out the many croc-inhabited bodies of water in the park. ( ABC Radio Darwin: Jesse Thompson )

Mr Lindner has worked in the park since 1986 and its resident crocodile population has varied greatly since his first day.

Hunting was banned in 1971 and the population rapidly expanded until 1988. The river systems in the park have begun to reach capacity in the three decades since.

Keeping track of croc numbers is a job that allows Mr Lindner to entertain his fascination with the creatures, but managing interactions with daring humans means it can also be a traumatic one.

There have been five croc fatalities in the park and Mr Lindner has responded in four.

Most recently in 2017 he was part of the team that joined Gunbalanya police to locate a man who went missing at Cahill's Crossing, only to be found with a 3.3-metre crocodile downstream.

Several people have died in the waters of the notorious floodway. ( ABC Radio Darwin: Jesse Thompson )

"So in that situation there, it's very important for us to get that person back to his family," he said, solemnly.

The ABC recently joined Mr Lindner in the field to learn more about one of Australia's most notorious waterways — the cars that get washed away, the apex predators which live there and the people who still wade in to cast a line.

Costly car graveyard

It's about a month after the crossing reopened for the dry season and a few hours after low tide; the current is still high and strong enough that most travellers pause before driving across.

The crossing is surrounded by the evidence of less fortunate travellers, including four vehicles tipped at various angles after being washed off.

An ill-fated car with seven passengers entered the floodway when waters were 1.4 metres high. ( ABC Radio Darwin: Jesse Thompson )

"We had seven people in a vehicle; a male driver drove in at 1.4 metres with a really strong current," Mr Lindner said of a barely visible four-wheel drive downstream.

The graveyard of cars is iconic, but it is also a source of headaches for emergency responders who field late-night phone calls about people getting stranded while trying to cross.

There are currently four abandoned cars at the crossing; this is the only sedan among them. ( ABC Radio Darwin: Jesse Thompson )

It also poses problems for rangers and traditional owners.

"There's a cost factor with all this; at the moment we're on a real tight budget and sooner or later we're going to have to source some money to get those vehicles out," Mr Lindner said.

"Traditional owners in the area want them out for two reasons: they're an eyesore — it spoils a pristine picture — and there are contaminants coming out of the vehicles — diesel, oil, fuel — polluting a pretty clean river system."

A lot of crocodile

The flowing water looks uninhabited but Mr Lindner is quick to spot a snout peeking through the water upstream.

As the tide recedes, washed-away cars are revealed. ( ABC Radio Darwin: Jesse Thompson )

He estimates there are another four or five crocodiles submerged in the immediate area and more will make their way to the East Alligator River as smaller waterways dry.

"You might have seven or nine crocs per kilometre and a biomass in the upstream section of over a tonne of crocodiles per kilometre, and up to two tonnes of croc in a certain stretch," Mr Lindner said.

"That's a lot of crocodile."

The crocodile downstream on the day the ABC visited kept its distance.

"The other day I was at the service station refuelling a boat with one of my colleagues, and a fisherman who lives in Jabiru came up and reported a two-and-a-half metre crocodile coming up to his boat at the South Alligator boat ramp," Mr Lindner said.

The croc came within two metres of the boat, its acute sense of smell may have been drawn to the scent of fish. Mr Lindner described this behaviour as overtly inquisitive, typical of crocs near boat ramps.

Upon receiving this information his team would typically set to work.

What a difference a few hours makes — as the tide rises people wait at the crossing's edge while some fish. ( ABC Radio Darwin: Jesse Thompson )

"Crocs in modern times are used to a non-threatening presence in people, but when you capture a croc, process it, totally secure his jaws, bound him, you take a croc well and truly outside his comfort zone and that animal's totally secure and in your custody, so to speak," Mr Lindner said.

"By the time you release it, it probably thinks it's escaped a near-death experience so it has a different perspective on people after that."

But not all crocs are as fearful.

First contact populations

In 2002, the death of a German tourist — Kakadu's first crocodile fatality since an attack at Cahill's Crossing in 1987 — drew attention to the park's management strategies.

"She was swimming in deep water, about 11 o'clock at night, and she was taken by a 4.6-metre croc in a place called Sandy Billabong," Mr Lindner recalled.

Mr Lindner has worked in Kakadu National Park since 1986. ( ABC Radio Darwin: Jesse Thompson )

The Kakadu Park Crocodile Management Strategy, released two years later, recognised that rangers could capture, relocate and/or destroy problem crocodiles.

But the likelihood of interaction is on the rise, according to the Kakadu Park Management Strategy 2016-26, and "park visitors continually need to be reminded of the associated risks".

"We're in a Commonwealth reserve; it's a world-listed area for cultural and national values and crocodiles are a part of that," Mr Lindner said.

The crocodiles are valued by the local traditional owners.

"They'll say 'Ginga [the local word for saltwater crocodiles] are not the problem, it's people'," Mr Lindner said.

Working closely with the ancient reptiles is fascinating but can also be traumatic. ( ABC Radio Darwin: Jesse Thompson )

It's a culturally significant time to be at the park, as crocodile populations return to what they were before tourism brought tens of thousands of visitors to Kakadu each year.

Part of Mr Lindner's job is to make sure attitudes towards the creatures change.

"We're seeing a population of crocs now that was probably seen at the time of first contact," he said.

"We've got to replicate that attitude now in the modern times, that crocs are still here, they haven't changed their behaviours or their habits, and we've got to exist in this environment but in a safe way because that risk is still here."