The biggest wave ever surfed?

Picture: Supplied/Reuters

Big wave surfer Garrett McNamara is believed to have set a new record after riding a 30-metre high wave in Nazare, Portugal.

Hawaii native McNamara is a legend in the sport, known for his death-defying surfing adventures in notorious breaks around the world.

The size of the wave is yet to be verified, but if it is as large as reported, the ride would had shattered the world record previously set by McNamara.

In 2011 the 45-year-old entered the history books by surfing a 24-metre wave, also in Nazare.

McNamara took to social media to express his excitement over the colossal surf.

"Thank you for all your support. It means the world to me. Today was an awesome day and so fun to be out there," he said on Twitter.

"I love Nazare. Cant wait for next year!!!"