A "rogue" wave inundated the coast near Pacific Beach in Washington this weekend — and it was all caught on camera.
Luckily no one was caught in the water at the time, but what exactly caused the "mini tsunami"?
Called rogue, freak or killer waves, this phenomenon has been a part of marine folklore for centuries. But rogue waves have only recently been accepted as an actual scientific event.
Since they are so rare, these walls of water are not highly documented and there is still a lot that scientists don't know about how and where these waves form.
According to the National Oceanic and Atmospheric Administration, there are two main processes that can lead to an extreme wave.
The first way is called constructive interference. This is when swells traveling across the ocean sometime do so at different speeds and directions.
Sometimes the crests and troughs actually coincide and reinforce each other — sort of like adding two waves together to get one big wave.
The other process is when a storm produces waves that move against the normal wave direction. An interaction can take place that leads to the two waves joining together to form one big wave.
In both cases, two waves align crest to crest and the amplitude is additive.
Rogue waves can end up over 30 meters high and seem to appear out of nowhere.