Lance Karlson was walking with his two-year-old daughter along the beach Geographe Bay in Dunsborough.
All of a sudden, they saw the tentacles of an octopus whip out of the water at a seagull.
Curious at the sight, Karlson pulled out his phone and started filming. The octopus started swimming towards him, lashed its tentacles at them before retreating.
Later, Karlson went swimming and found the octopus sitting on a bed of shells.
As he was looking at the shells, the octopus attacked him, striking him on the arm and connecting to the back of his neck. My goggles were too fogged to see what had happened and I swam back to shore in pain, Karlson said. The imprints of the tentacles quickly formed raised marks across my skin.
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A man has been attacked by an octopus while swimming at a picturesque beach in Western Australia.
Geologist and author Lance Karlson was about to take a dip near the resort he and his family were staying at in Geographe Bay, on Australia's southwest coast, when he spotted what he thought was the tail of a stingray emerging from the water and striking a seagull.