Three Danish tourists who spent a night on top of their flooded four-wheel-drive while a crocodile lurked nearby have told how they plotted their escape over six terrifying hours.

Upon reaching land, Julie Lelund, 21, Alexander Jensen, 22 and Neikolaj Nielsen, 22, walked 10 kilometres before finding help and were sheltered for 10 days by a remote Aboriginal community.

The tourists were travelling through the Top End when they attempted to cross the Robinson River in the Gulf of Carpentaria, when they hit a rock and the car stopped.

"We weren't able to start it, but 10 seconds later water started coming through the car doors," Mr Jensen said.

"So we had to roll the windows down and crawl up to the roof and try to call for help, but there was no reception, so yeah, we were unfortunate."

Alexander Jensen and Julie Lelund arrived in Darwin after 10 days in a remote Aboriginal community. ( ABC News: Lucy Marks )

The trio drove into the rising river — known by locals to be full of crocodiles — about 1:00am on January 22.

"The water was very brown so we couldn't see through the water — it was all dark but there was the emergency light blinking so we could see a little," Ms Lelund said.

"And then we saw two yellow eyes in the water, so it was really scary.

"It looked really big, we only saw the top of the head and the eyes, but we could see it was not a baby croc because in the other rivers, in the small creeks, we saw some small crocodiles but with this one it was bigger, definitely bigger.

"And when we came to the community, there were tales of the big crocodile who lives in the river, like 4 metres or something."

Areas of the Top End have been inundated by floodwaters for more than a week with an active monsoon bringing heavy rains and damaging winds.

'We had plenty of time to plan our escape'

In the six hours the group spent on top the car, they decided to gather essential supplies — like food, water and socks — and waited for daybreak.

"[I] was a little panicking, but we just relaxed and said we had to wait for the croc to go and then had plenty of time to plan our escape," Ms Lelund said.

"So we got all of the important stuff and then we decided to take the roof rack off the car in case the croc came back when we got in the water."

The trio climbed onto the roof of the car to escape the floodwaters. ( Supplied: Alexander Jensen )

Mr Jensen said they did not believe anyone would come to rescue them because of the rain, so they decided to take matters into their own hands and wade through the water to land.

"We slept for a couple of hours and then we waited a little, so we were on the roof until 7:00am in the morning and then we decided to go for it," Mr Jensen said.

"That was probably the most scary thing about the whole situation: going into the water.

"We looked around but we couldn't see any crocs, but we couldn't be sure, so we used the roof rack as a shield."

Aboriginal community sheltered tourists for 10 days

Once the trio got to the river bank, they decided to walk toward what they believed was the nearest town — Borroloola, 108 kilometres away.

After 10 kilometres on foot, they were picked up by a car who took them to the Aboriginal Robinson River community, about 50 kilometres away.

"We started crying because people asked us what had happened and it was a bit shocking and relieving at the same time," Mr Jensen said.

"[The people in the community] gave us a house we could stay at, and gave us clothes and food, and made us feel like home until we could get away on a plane.

"We're so grateful that they took so good care of us and made us feel like home."

Julie Lelund, Alexander Jensen (centre) and Neikolaj Nielsen about to board a plane from Borroloola. ( Supplied: Alexander Jensen )

People from the community also helped the Danish tourists retrieve the car from the river, when the water subsided.

"They suspected someone looted the car. All our belongings are gone," Mr Jensen said.

Due to the severe monsoonal weather, it was another 10 days before they could board a plane out of Borroloola to Darwin, with the help of some visiting teachers.

'We underestimated the wet season'

After travelling through Australia by car for six months, Mr Jensen said they did not think becoming stranded could be a risk.

Map The tourists attempted to cross the Robinson River when they got stuck.

"We underestimated the wet season a bit, I just thought it was rainy all the time but we couldn't imagine all the roads could be flooded and we could be stuck in an Aboriginal [community] for almost 10 days," he said.

Ms Lelund said when atop the car, she feared the ordeal could end in very different circumstances.

"In my head, the worst case scenario was someone got hurt or if we stayed on the car until someone would come and they never would've come because the weather was so bad," she said.

Ms Lelund and Mr Jensen became engaged just three weeks earlier on New Year's Eve in Sydney, and say they will have quite the story to tell their families.

The pair and Mr Nielsen will return to Denmark next week.