A US kayaker has beaten off a hammerhead shark with a paddle after it attacked him off the Californian coast.

Mark McCracken, 33, filmed the 15-minutes encounter off Gaviota State Beach, near Santa Barbara, and later posted it onto his Instagram account.

The Santa Maria construction worker, who describes himself as a fishing enthusiast, claims the hammerhead shark was “super aggressive” towards him.

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"It hit the back of my kayak twice and I turned around to see it," he told CNBC News.

"I couldn't tell if he was biting [the kayak] or if he was head-butting it but soon as I saw it I just started going at him with the paddle."

Commenting on his post, Mr McCracken said he “had to hit him over 20 times before he finally gave me some space but still stalked me for half mile all the way back to shore.”

He added: “Pretty bizarre and crazy experience to say the least.”

Only three types of nine Hammerhead species, the largest of which is the Great Hammerhead, have been known to attack humans and it remains unclear what species attempted to bite Mr McCracken.