Daredevil surfer Garrett McNamara claims to have broken his own world record after conquering what appeared to be a 30m-high wave off the coast of Nazare, Portugal yesterday.
Footage of the feat shows the 45-year-old Hawaiian surfer riding straight down the crest of a gigantic wave that rises above the roof of a lighthouse building where onlookers are seen standing in the foreground.
If he had wiped out, McNamara risked being dragged deep underwater or even slamming into a reef on the ocean floor.
"Today was an awesome day and so fun to be out there," McNamara tweeted.
"Thank you for all your support. It means the world to me."
Nazare is renowned for big surf, thanks to an underwater canyon 300m deep and 5km wide that acts like a funnel when it receives Atlantic swells, creating huge waves.
McNamara set the current world record at the same location in 2011 when he successfully surfed a 24m-high break a record confirmed by a panel of experts at the annual Billabong XXL Global Big Wave Awards.
The height of yesterday's big wave is yet to be verified.
McNamara has previously said he puts a lot of careful planning into big wave riding but once he is in the water, "100 percent instinct" takes over.
"It's a very thought out, well-planned mission but once you get in the water and you're at the spot there's always the unknown and you just have to deal with it as it comes," he told ABC News in an interview after his 2011 world record.