Riding a 100 foot wave has always been the holy grail of big swell surfing.

But with spots like Portugal's big wave mecca, Nazare, continuously throwing up monster rides, the tough part is actually getting a proper measurement of wave height.

In 2013, Brazil's Carlos Burle and Hawaii's Garrett McNamara rode what were described as 100 foot waves at the big swell magnet.

Now, footage has emerged of yet another 100 foot (33m) wave being conquered at the popular seaside resort.

The recently captured video, shows a yet to be identified goofy-footer drop down the face of wall of water the equivalent of a 10-storey building and with amazing skill and strength hold his line across a foamy section to conquer the beast.

Although the metric system dominates, surfers still measure waves in feet, hence the 100 foot reference.

But even that measurement has been called into question by many board riders because of the relatively flat wave that breaks at Nazare Canyon.

Unlike other big swell spots, such Jaws in Hawaii and Mavericks in California, which both break top to bottom with pitching lip above the trough of the wave, Nazare is not as steep.

It means a wave face measuring 100 feet is actually closer to 60 feet in height.