Watch Large Tiger Shark Attack Kayak Off Hawaii Coast

Scott Haraguchi was fishing in his kayak over a mile offshore from Kualoa in Windward Oahu when the GoPro he’d accidentally left on after catching a fish caught some terrifying footage.

"I heard a whooshing sound that sounded like a boat heading towards me without the motor and I looked up and I saw this big brown thing. My brain thought it was a turtle, but then I got slammed by it and realized that it was a tiger shark," Haraguchi told KITV Island News.

Haraguchi managed to kick the shark away from his kayak and kept fishing. He said he was running on adrenaline at the time, but didn’t realize the magnitude of the shark encounter until he reviewed the footage.

He's unsure why the shark attacked, but says shortly after he noticed what appeared to a wounded seal and believes the shark may have mistaken his kayak for its wounded prey.

The next day, a 20-foot shark sighting prompted officials at Marine Corps Base Hawaii to close North Beach and post signs.

Concerned about the recent sightings, Haraguchi says he'll always bring a partner when going fishing.

He also realizes how fortunate he is.

"I realize that life is short. Time is short on Earth, so make the most of it," he said.