Austin swam 4 kilometres to shore to raise the alarm after being swept out to sea with his mother and siblings. (ABC News: Briana Shepherd)

In short:

Austin Appelbee, his mother and two siblings were swept out to sea off Quindalup in WA’s South West.

The 13-year-old has recounted swimming 4 kilometres to shore to get help for his family, who were rescued after spending up to 10 hours at sea.

His mother Joanne said sending him to shore amid rough seas was “one of the hardest decisions” she has ever made.

A mother who sent her 13-year-old son to swim 4 kilometres back to shore after the family were swept out to sea in rough conditions off WA’s South West says it was “one of the hardest decisions” she has ever made.

Joanne Appelbee and her three children had been holidaying at Quindalup, about 250 kilometres south of Perth, and had set out from the beach on a kayak and inflatable paddleboards in seemingly calm conditions on Friday morning.

The family had planned to be out for an hour, leaving their picnic rug on the beach and taking no water or food with them.

But they soon ran in to trouble as the sea became rough, causing their kayak to flip and take on water as they started getting pushed further out to sea around midday.

13-year-old Austin Appelbee recounts his heroic four-hour swim through rough seas to help his family.

“One of the hardest decisions I ever had to make was to say to Austin, ‘Try to get to shore and get some help, this could get really serious really quickly,’” she said.

“I knew he was the strongest and he could do it.

“I would have never went because I wouldn’t have left the kids at sea, so I had to send somebody.”

Austin (right) and his brother Beau, mother Joanne and sister Grace (left to right) have recounted their ordeal. (ABC News: Briana Shepherd)

Austin said he initially tried to tow his family back to shore on a kayak before his mum made the heart-wrenching decision to send him for help.

“I started paddling to shore on the kayak … but it kept taking on water and I was fighting rough seas and then I thought I saw something in the water and I was really scared,” he said.

‘Just keep swimming’

The brave teen then decided to ditch both the kayak, which he said was pulling him further out to sea, and his life jacket, which was impeding his swimming, and attempt the marathon swim to shore.

“I was trying to get the happiest things in my head, and trying to make it through, [and not think of] the bad things that will distract me,” he said.

“And at this time, you know, the waves are massive, and I have no life jacket on … I just kept thinking ‘just keep swimming, just keep swimming.

“And then I finally made it to shore, and I hit the bottom of the beach, and I just collapsed.”

Volunteers point out the location of the rescue in Geographe Bay. (ABC South West WA: Madigan Landry)

It took Austin about four hours to swim the four kilometres to shore.

He said he then ran about 2 kilometres back to their accommodation, where he got his mum’s phone to call emergency services.

“I said, ‘I need helicopters, I need planes, I need boats, my family’s out at sea.’ I was very calm about it,” he said.

A multi-agency rescue team was mobilised, including WA Water Police, a rescue helicopter and Naturaliste Marine Rescue.

Aerial crews were able to spot the family.

They found Austin’s mother, Joanne, brother Beau, 12, and eight-year-old sister Grace about 8:30pm, drifting in the ocean about 14 kilometres offshore.

Rescuers said Austin’s detailed account of the kayak and paddleboards helped them find the family, describing his swim to shore as “superhuman”.

Austin said he had started swimming lessons when he was four and did VacSwim, but had previously found it “quite tiring” to swim 350 metres without a break.

Naturaliste Marine Rescue volunteers helped locate the family after the boy swam to shore. (ABC South West WA: Madigan Landry)

‘We kept positive’

Joanne said the trio had been stranded in the ocean for between 8 and 10 hours and had initially remained hopeful.

Joanne has also been hailed a hero for keeping her son and daughter together while waiting for help. (ABC News: Briana Shepherd)

“We kept positive, we were singing, and we were joking and … we were treating it as a bit of a game until the sun started to go down, and that’s when it was getting very choppy [with] very big waves,” she said.

“As the sun went down, I thought something’s gone terribly wrong here and my fear was that [Austin] didn’t make it.

“Then, as it got darker, yeah, I thought there was no one coming to save us.

“We were cold, we were shaking, and Beau had lost feeling in his legs.”

Joanne said she was mentally preparing for all of them to die, yet she continued to comfort her children.

“It was the end, it was definitely the end,” she said.

“My Mum is in Ireland … I remember looking up at the sky, going, ‘Mum, if you can hear me, just light that holy candle for me.’”

Family separated

Joanne had used leg braces to tether the family to the paddleboards, but Beau said the trio became separated around 5 minutes before they were rescued.

“Towards the end, a big wave hit all of a sudden, and my little sister and I were like on a weird angle, and it flipped us off, and we floated away from Mum,” Beau said.

Joanne and her family spoke to reporters before school on Tuesday morning. (ABC News: Briana Shepherd)

Joanne said she could hear Grace screaming as the rescue boat approached, but could not hear Beau.

“When the boat came and picked me up, and I screamed at them that there were two kids [still] in the water … I called for Grace, and I could hear her, and I still couldn’t hear Beau.

“I called out to kill the engine, and all of a sudden, I heard this little voice … and we picked them up, and it was the best feeling in the world.

“But I still didn’t know about Austin … So it was very, very frightening.”

‘I thought they were dead’

After phoning authorities, Austin said some “nice ladies on the beach” gave him food before he “just passed out”.

He was taken to Busselton Health Campus where he later woke up, unaware of what had happened to his family.

Austin tried to reach land on his kayak before it took on water in rough seas, then swam the rest of the way. (ABC News: Briana Shepherd)

“I realised they were gone, I thought they were dead,” he said.

“I had a lot of guilt in my heart. I thought, ‘Oh man, I wasn’t fast enough.’”

But a short time later, he received the happy news that his family had survived.

The family were stranded in rough waters around 14km off the coast in Geographe Bay in WA’s South West. (ABC South West Anthony Pancia)

Austin is on crutches to help his sore legs bear his weight after being told the physical exertion he endured was equivalent to running two marathons.

The ordeal has left Joanne, Beau and Grace with swollen legs, blisters, bruises and a rash from getting on and off the paddleboard.

“My fear is more the mental scarring for these children as time goes on, which is something we’re going to look deeply into,” she said.

“And I just hope that [the experience] doesn’t come back later on to hit them harder than it should.

“Because as I said to everybody, we made it, we’re alive, and that’s the most important thing.

“I have three babies. All three of them made it. That was all that mattered.”

Premier Roger Cook offered his praise on social media, declaring Austin a “true West Aussie hero”.

“Austin’s bravery is beyond his years, showing remarkable courage, resilience and determination in the face of real danger,” he wrote.

“Well done, Austin — we’re so proud of what you’ve done.”