Sounding cool, calm, and collected, at first blush you wouldn’t think Austin Appelbee was in desperate fear for his family’s lives.

The 13-year-old boy made headlines for his heroism after he swam four kilometres in the ocean to get help for his stranded family in Geographe Bay, near Quindalup in Western Australia.

Now, with permission from Austin’s mother Joanne state police have taken the very unusual step of releasing the audio of the Triple Zero phone call Austin made when he at last reached the shore.

Austin Appelbee swam 4km through the ocean to find help for his stranded family. (Nine)

The family, including Austin’s mother Joanne, his brother Beau, 12, and sister Grace, 8, had been swept out to sea while kayaking and paddle-boarding in rough conditions on January 30.

As the light faded, Austin said his mother asked him to turn back and try to find help on shore.

Austin first had to abandon his kayak when it began taking on water, then took off his life jacket when it interfered with his swimming.

Joanne Appelbee with Austin (left). (Today)

After his 4km race back to shore, he then ran a further 2km to find a phone and call Triple Zero at about 6pm.

“My name’s Austin and I’m outside on the beach,” the audio begins.

“I have two siblings, Beau and Grace. Beau is 12 and Grace is eight. We went on a kayak trip and a paddleboard trip, and we got out to sea and we got lost out there and it – we got lost around about, I don’t know what time it was but it was a very long time ago.

The family came into trouble while kayaking and paddleboarding at Geographe Bay. (Nine)

“We couldn’t get back to shore and mum told me to go back to get help. And then, I haven’t seen them since. I think they’re kilometres out in the sea.

“I think we need a helicopter to find them. I’m sitting on the beach right now and I have to explain, I think I need an ambulance because I think I have hypothermia.”

Despite his desperate worry over his family, Austin continued to speak with clarity and calm to the emergency operator as they asked more about the situation.

“I don’t know what their condition is right now and I’m really scared,” he said.

“I had a kayak and then the kayak had a bunch of water in it and started to sink.

I had to swim around about 4km facing the current. I’m extremely tired, I’ve got heatstroke, and I feel like i’m going to pass out, I’m very dizzy.”

He went on to give the time they’d started their ocean trip, and that he couldn’t see them from the shore.

The recording stops after Austin says he’s been onshore for only 10 minutes.

Austin’s family were found at about 8.30pm, clinging to a paddleboard, and they were brought in safely.

Police have praised Austin’s cool head during his Triple Zero call as crucial to the massive rescue operation.

“What Austin did was nothing short of extraordinary,” Forward Commander Acting Sergeant Andrew McDonnell, who coordinated the rescue, said.

“His bravery and courage in those conditions were remarkable, and his actions were pivotal in bringing about a successful outcome.”

You can listen to the audio of the call in full in the player above. WA Police officers also discuss it in their new podcast “Operation Podcast”, available on Apple and Spotify.