8-year-old who survived river drowning tragedy details how she escaped from sinking car.

Three weeks ago, 43-year-old Stephanie King tried desperately to save her children when the van she was driving veered off the into the raging Tweed River in northern New South Wales.

When her body was retrieved from her vehicle by police divers, she was found holding one of her children.

Stephanie, along with seven-year-old son Jacob and 11-year-old daughter Ella Jane, were killed in the tragedy.

Only one of Stephanie's children, eight-year-old Chloe, was able to escape the sinking vehicle and make it to safety.

For the first time, Chloe has spoken of the horrific incident, telling reporters how she managed to free herself.

"I unbuckled my seat belt, I tried to go up for air and I just kept floating up," Chloe told 7 News.

"And then I got out."

She told reporters she swam to the shore, and hiked to the nearest farmhouse to get help.

"They just took me in, and lent me some clean clothes and cleaned up the cuts on my feet," she said.

Chloe’s father, Matt Kabealo, said he was "shattered" by the loss of his wife and two of his children, and admitted he was "not holding up".

"I'm just being strong for my daughter," he said.

He added that his children would be "absolutely over the moon" with the amount of support the Australian public has offered to the grieving family.

"[Stephanie] was a beautiful woman and they were beautiful children, and they deserve [this support]," he said.

Chloe added that her siblings and mum were "all loved".

"They will never be forgotten," she said.

Police believe the mother of three lost consciousness while trying to free her children from the crash.

"That woman is a hero, she died trying to save her children," LAC Superintendent Wayne Starling told the media when the vehicle was recovered from the Tweed River.

"I have no doubt she would still be alive if she wasn’t trying to save her children."