Hero schoolboy swims for four hours in rough seas to save mother and siblings

His remarkable journey to shore covered four kilometres, with the boy removing his life jacket halfway through and continuing for another two hours without it.

The family, who were on holiday in the South West region, had been using inflatable paddleboards and a kayak when strong winds pushed them offshore from Geographe Bay.

The boy initially attempted to paddle back to shore in the kayak to seek help, but the vessel began taking on water.

He was forced to abandon the craft and swim the entire distance himself.

Western Australia police received a report at 6pm on Friday that a family had been swept out to sea.

A multi-agency search and rescue operation was quickly mobilised.

The response included WA water police, local marine rescue volunteers and the state's rescue helicopter.

His 47-year-old mother, 12-year-old brother and eight-year-old sister had been treading water in rough conditions for hours before rescuers arrived.

A helicopter located the three family members at 8.30pm, finding them clinging to a paddleboard roughly 14 kilometres from shore.

Paul Bresland, commander of Naturaliste Volunteer Marine Rescue, said the family had been in the water for hours before being spotted.

A volunteer marine rescue vessel was directed to their position and successfully retrieved all three.

Bresland noted that the 13-year-old had provided detailed descriptions of the kayaks and paddleboards, including their colours, which proved invaluable to the search effort.

The family were assessed by St John WA paramedics at the scene before being taken to Busselton Health Campus for further medical evaluation.

A spokesman for St John WA described the rescue as "remarkable" and said he "praises the teenage boy for his brave actions."

South West Police Inspector James Bradley thanked everyone involved in the successful operation and warned that ocean conditions can change rapidly.

"Thankfully, all three people were wearing lifejackets, which contributed to their survival," he said.

"The actions of the 13-year-old boy cannot be praised highly enough, his determination and courage ultimately saved the lives of his mother and siblings."