This surfer was wiped out and swallowed whole by an enormous 60ft wave off the coast of Portugal.
The athlete can be seen speeding along the black and white wall of water as it breaks at Nazare on the Atlantic coast.
Then, he plunges underwater as the wave collapses in a mass of white foam.
A very strong wave can push a surfer 20 to 50 feet below the water, where the pressure is so high it can rupture their eardrums.
Currents can also push surfers towards hazards such as rocks or coral reefs.
There is also a risk of consecutive waves holding the surfer underwater for a long period of time, potentially leading to drowning. However, deaths are rare.
Nazare is a hotspot for big wave surfing, with giant swells generated by an underwater canyon just off the coast.