A mother has described the terrible moment she sent her 13-year-old son into rough seas to swim four kilometres to shore after her family became stranded off the coast.

Joanne Appelbee, 47, and her three children were found 14km from the shoreline at Quindalup, 250km south of Perth, after strong winds pushed their kayaks and inflatable paddleboards out to sea on Friday.

Her 13-year-old son Austin jumped from his kayak and swam to shore, completing the first two kilometres in his life jacket before abandoning it for the final stretch.

He eventually made it out of the water, where his detailed descriptions of the kayaks and paddleboards helped rescuers locate his stranded family in under an hour.

‘One of the hardest decisions I ever had to make was to say to Austin, try and get to shore and get some help,’ Ms Appelbee said, WA Today reports.

‘This could get really serious, really quickly.

‘I could see the danger in [the situation], with getting dragged out a bit too far, and the waves kept coming and getting stronger.’

After finally reaching the beach, Austin then had to sprint 2km to find a phone and call local authorities.

Joanne Appelbee, 47, and her three children were on the water at Quindalup, 250km south of Perth, when strong winds pushed their kayaks and paddleboards out to sea last Friday

Austin, 13, swam 4km to shore and then sprinted a further 2km to call for help

Within an hour of the search being launched, the family were found treading water

WA Water Police, local marine rescue volunteers and a rescue helicopter were deployed in the multi-agency search at 8.30pm.

Ms Appelbee, her 12-year-old son and eight-year-old daughter were found within an hour and were towed to shore by a rescue boat.

The exhausted mother described the fear she felt at the thought that no one might come to rescue her and her children.

‘It was pretty terrifying for a while, and I lost my glasses, so I definitely couldn’t see much, and I knew we were extremely far,’ she said.

‘There’s no bigger word to describe [Austin], other than proud… I’m speechless at his efforts,’ she said.

‘But at the same time, I knew he could do it.’

Austin told reporters he repeated to himself ‘just keep swimming, just keep swimming’ during the hours-long effort to get help.

‘I just said… “not today, not today”. I did breaststroke, I did freestyle, I did backstroke. I hit the bottom of the beach and just collapsed,’ Austin told Sky News on Tuesday.

Ms Appelbee said it was one of the hardest decision of her life, telling Austin to swim to shore

The family reunited with the rescue crews after they were discharged from hospital

‘And after that, I had to sprint 2km to get to the phone.’

South West Police Inspector James Bradley praised Austin for the accurate descriptions of the kayak and paddleboards he provided to rescuers.

‘The actions of the 13-year-old boy cannot be praised highly enough,’ he said.

‘His determination and courage ultimately saved the lives of his mother and siblings.’

They were assessed by paramedics and taken to Busselton Health Campus.

The family was reunited with rescue crews after they were discharged from hospital over the weekend.

Mr Bradley added the family’s use of life jackets had contributed to their survival, serving as a timely reminder to other holidaymakers.