A surfer from America is claiming a new world record for surfing the biggest wave ever.
Garrett McNamara was in a surfing competition on the coast of Portugal, when a massive wave built up behind him. He managed to stay on his surfboard despite the wave crashing into him.
It's difficult to measure waves but estimates are that Garrett's wave was about 30m high! That's the same as five houses or 15 tall men.
The previous world record was 24m.