An Australian family narrowly escaped the wildfire flames that closed in on them by jumping in the water at the edge of their property, and taking refuge under a wooden jetty.

Tim Holmes, his wife Tammy and their five grandchildren, aged 2 to 11, fled their burning home near Dunalley, in Tasmania, and took shelter in the sea last Friday as wildfires raged across southern Australia amid record-high temperatures.

"We saw tornadoes of fire just coming towards us," Holmes told the Australian Broadcasting Corporation (ABC) on Monday. "And the next thing we knew, everything was on fire, everywhere all around us."

Their only refuge was to head down to the jetty, he said.

"There was no other escape … The difficulty was there was so much smoke and embers, and there was probably 200 millimetres to 300 millimetres of air above the water," Holmes said.

"So we were all just heads; water up to our chins just trying to breathe because it was just — the atmosphere was so incredibly toxic."

Despite the hot temperatures, the water was very cold and the family huddled for warmth.

"[The fires] raged for three hours.… it was a wooded point. So everything was on fire and it was just exploding all over the place," Holmes said.

Mom braced herself to lose kids, parents

Bonnie Walker, Holmes's daughter and the mother of all five children, and her family live in a home next to her parents, but was away at the time because she had a funeral to attend to, she told the ABC.

Meanwhile, her husband, David, was also away, hiking along Tasmania's southern coastline, the ABC reported. The couple left their kids in the care of her parents.

Walker's drive to the funeral in Hobart was cut short, however. Roads were shut down due to the rapidly spreading fires, she said.

"We just waited by the phone and received a message at 3:30 to say that mum and dad had evacuated, that they were surrounded by fire, and could we pray.... So I braced myself to lose my children and my parents," she told the ABC.

When the flames subsided, Holmes managed to grab a small boat, and loaded his wife and the children into it, said Bonnie Walker.

"My father rallied against all odds and managed to go up and get a little dinghy off the foreshore. Loaded our children in and my mum, and then dragged it into a headwind 200 metres or 300 metres around the point into the headwind. And got them to safety so that they weren't breathing the polluted air."

Their houses and all their belongings are gone, but David Walker says the family is simply happy to be reunited, safely.

"All the things that we've lost, yeah, there's some precious memories there. But they can be replaced, material things," he told the ABC. "But my wife and children, not so easily replaced. Yeah, I just feel blessed that my family's all together."

With files from The Associated Press