'I was sure I was done' - terrifying video of shark attack emerges

Frightening new footage has emerged of a shark attack in the United States, in which a shark bites into a man's kayak. 

Brian Correiar, who Fox News reported is an experienced scuba instructor, was out kayaking in Monterey Bay in California in March when he was attacked by a great white shark.

A newly released video filmed by a spectator onshore shows the moment the shark rammed into his kayak. 

"It all started with a bang," Mr Correiar said in an interview with National Geographic. "Suddenly the kayak was launched into the air and I fell halfway out of it."

As he was mere metres away in the water, the shark bit into it.  

"[It] proceeded to munch along the entire length of the kayak while never leaving the water's surface, easily rolling it over length-wise like a toy," he said. 

He told National Georgraphic the shark lunged toward him, with the kayak still in its jaws.

"It was like a horror movie. The shark came toward me, dropped the kayak, then dove straight down below me where I couldn't see it," he said.

"I was sure I was done."

Gene Mace, who was recording the attack back on shore, can be heard telling his wife to "call somebody."

Soon after, the Coast Guard arrived to rescue the kayaker.