Big great white shark bumps into boogie boarder in Western Australia

A man has been treated for shock after he was knocked by a great white shark while boogie boarding in Western Australia's south.

The man was less than 50 metres offshore at Casuarina Point in Bunbury on Sunday when the shark bumped his board.

A man was knocked by a great white shark while boogie boarding. Source: WA Police

He was shaken by the close encounter but managed to make his way back to shore and raise the alarm, which prompted the beach to be closed, a Surf Life Saving WA spokesman told AAP.

A St John Ambulance spokesman said the man had been treated for shock but was not injured and did not need to be taken to hospital.

Earlier on Sunday, Surf Lifesaving WA tweeted about the incident: "Public report large white shark sighted 08:49hrs 11/06, Point Casuarina, Bunbury 50m offshore , Cassaurina Drive, Outer Harbour."

Reports claim the shark was more than four metres long.

A man has been treated for shock after he was knocked by a large shark while boogie boarding. Source: WA Police

Witness Martin Lottering said he was in the look-out tower when the incident occurred. He told WA today he had been looking at fishing boats on the water with his binoculars.

"I spent some time watching the guys in the water on their bodyboards, and eventually I noticed a swirling and thrashing in the water next to one of the guys," Mr Lottering told the publication.

He said he saw the shark's head come out of the water and a bodyboarder knocked off the board.

"When this happened I could see the shark's dorsal fin next to the board, and then I realised how big he was. His dorsal fin looked about half the size of the bodyboard."

Hungry Hollow beach has also been closed following the incident.