A West Australian man has won the top prize at a national surfing competition for big wave riders.

Jarryd Foster, 27, won the biggest wave category at the Oakley Big Wave awards announced in Sydney on Wednesday night.

Foster grew up surfing big swell on the south-west coast, including the infamous Cowaramup Bombora break - known to locals as Cow Bombie - near Gracetown.

Originally from Yallingup, he moved to Tasmania two years ago, but was on holiday in WA when he borrowed a wetsuit and board to surf the break which won him the prize.

"Something just lined up for us that day, it was the day you dream of," he said of the conditions.

"I got towed into this wave, on all borrowed gear, and it's turned out to be the biggest."

With photographic proof of his approximately 40-foot (12-metre) ride, Foster won $20,000 in prize money for his efforts.

"The waves this year were next level which is good, it's really pushing us all," he said.

Competition recognises underground surfers

The Big Wave competition has become a showcase of underground surfers, who do not typically promote themselves in the media or partake in surf competition circuits.

"It's about doing it because you want to, not to do media," Foster said.

"I started doing it without a camera and I'll keep on doing it without one."

Ironically though, it was the photo taken by friend Jamie Scott that won Foster the award.

Foster said the competition was not about the glory of the win, but the collegiality between surfers.

Sorry, this video has expired Surfers tackle the big breaks off WA's coast ( Nicolas Perpitch )

"We're all mates, we've all known each other forever, so it's just competition between ourselves, but with a big pay cheque at the end," he said.

"Everyone's happy that their mate gets the big one and vice-versa."

This year, 11 out of the 12 entries nominated across three award categories were from isolated, shark-infested breaks kilometres off the West Australian coast.

Mark Visser won the biggest paddle-in award, also for a Cow Bombie wave, and Chris Ross won biggest slab for his ride at The Right, which is off Walpole.

The Right breaks on a big granite boulder and the water surges up from 70m deep, making it one of the most dangerous waves in the world.

The finalists were chosen by the riders themselves, with every surfer who has ever registered for an award given the chance to vote for the best rides.