The hotel where watersport recreation gear was signed out by a family who went missing at sea for hours is being investigated.

Austin Appelbee, 13, bravely swam through four kilometres of rough surf to alert authorities that his mum and two younger siblings were stranded, clinging to paddleboards, off the coast of Western Australia’s South West on Friday.

WorkSafe said it was aware of the incident and is currently making preliminary inquiries with Club Wyndham in Dunsborough, 2.5 hours south of Perth.

WA Police also say the incident has been referred to the Australian Maritime Safety Authority.

Mum Joanne Appelbee said the family had signed out two paddleboards and a kayak for a 10am to 12pm block but did not get out onto the water until just after 11am.

Austin Appelbee, right, swam to save his younger brother Beau, sister Grace and mum Joanne.Austin Appelbee, right, swam to save his younger brother Beau, sister Grace and mum Joanne. Credit: 7NEWS

She said the family were overcome by the conditions and could not return to the beach as planned.

The alarm was only raised hours later when Austin, who had recently failed state-run program VacSwim, made the exhausting journey back to shore and sprinted to alert police about 6pm.

“I said, ‘I need helicopters, I need planes, I need boats. My family’s out at sea’,” he said.

“I was very calm about it. I think it was just a lot of shock.”

‘Had no reason to be alarmed’

Joanne, son Beau, 12, and daughter Grace, 8, were found by a rescue helicopter 14km off the coast about 8.30pm.

The hotel has launched its own review, telling 7NEWS: “Our guests are free to use resort equipment on a complimentary basis until late in the day”.

“Our staff had no reason to be alarmed. Guests are aware that the beach is outside the resort grounds, is unpatrolled, and that there is no direct view of the beach from the resort,” it said.

The Appelbee family was plucked from the water after more than eight hours.The Appelbee family was plucked from the water after more than eight hours. Credit: 7NEWS

“However as a matter of course the resort is conducting a safety review to minimise the risk of any similar incident occurring in the future.”

Joanne said swimming lessons were vital and life jackets “saved us many times over”, as they were knocked about by waves.

She said conditions were calm but changed “in the blink of an eye”.

The mother suggested hotels could supply a dry bag for mobile phones “to take out with you or maybe have better policies and procedures to follow up on people”.