A French tourist who walked out of the Kakadu National Park unharmed and completely unaware that his disappearance had sparked a mass search operation said he was passing the days quietly writing children's stories in a small cave.

Key points: French tourist Yann Buriet said he was not lost, but had decided to spend five nights camping under a rock shelter

French tourist Yann Buriet said he was not lost, but had decided to spend five nights camping under a rock shelter When he returned, he realised his disappearance had sparked police air, ground, and dive searches

When he returned, he realised his disappearance had sparked police air, ground, and dive searches Mr Buriet said tourists should ensure they tell someone where they are going

Yann Buriet, a 31-year-old beer brewer from the Bordeaux region in France, said he was not lost, but had decided to spend five nights camping out alone under a rock shelter.

"I was writing stories for children, philosophical stories, like simple situations for children but adults can understand in other ways," he told the ABC.

"I was in a little cocoon, and then I came out and I didn't expect this all to happen."

He said he had heard helicopters overhead, but was unaware they were looking for him.

"I thought it was just tourists, it was strange," he said

"And the next day I came out and realised it was all for me."

Searches of park fail to spot tourist

Kakadu park rangers raised the alarm with Northern Territory Police on Tuesday after Mr Buriet failed to return to his car, four days after he had been sighted by park staff on Saturday morning.

Mr Buriet's white Mitsubishi had remained located in the Gunlom Falls car park area since his disappearance. ( Supplied: NT Police )

Missing campers spark great concern in the remote jurisdiction as there have been a number of deaths in recent years.

One man, Alex Rosenberg, has been missing for a year since he disappeared while camping alone at Edith Falls, and three German tourists died while hiking in Central Australia.

Mr Buriet said he had been camping on the escarpment only a 15 minute walk away from the upper pool at Gunlom Falls, one of Kakadu's most popular swimming spots.

But he was not spotted by ground or air searches that swept through the area on Tuesday afternoon.

Queensland man Alex Rosenberg was last seen near Edith Falls campground. ( Supplied: NT Police )

He did not have a permit to camp at the site, and had not told anyone where he was going or how long he planned to stay, but said he had plenty of food and water.

He said he managed to contact his girlfriend and family after the ordeal to tell them he was okay.

"The Australian authorities got on to them pretty fast I think, they freaked out a lot, they were very scared," Mr Buriet said.

"But all good, after I contacted them again and said everything is fine."

'Leave a little piece of paper'

Mr Buriet said he realised his adventure was not over after he emerged from the bush, as police had taken his identification documents from his van, including his wallet, and he did not have much petrol left.

He said a hitchhiker he had picked up managed to sell a knife in Pine Creek to buy enough fuel to get back to Darwin, about 225 kilometres north-east.

"It was a journey to come back, because [the police] took my papers, wallet, money, and everything to Darwin," Mr Buriet said.

"I have nothing, no petrol in the car left, and no money to come back."

Now safely in Darwin and reunited with his papers and possessions, Mr Buriet wanted to pass on his thanks to everyone who raised the alarm or helped in the search.

"Thank you very much, for everybody, it's good to realise that [people help] if something wrong, it can happen fast," he said.

The French national was camping in a cave near Gunlom Falls. ( ABC Open: Heath Whiley )

He also has a message of warning to anyone planning on heading out bush.

"Leave a little piece of paper," he said.

"[Write down] the day you left, the day you come back, and if there is a way of having a permit, it's good to have a permit, too," he said.

Mr Buriet said he loved Kakadu and hoped he would one day return to the park.