Do you know what a “sneaker wave” is?
If you don’t, you will after viewing this terrifying caught-on-camera moment at Moonstone Beach in Humboldt County on Jan. 11.

Marcella Ogata-Day posted a video of a sneaker wave knocking three unsuspecting people off their feet near the beach parking lot.

“Everyone was okay and a lot more alert,” Ogata-Day said on her Facebook page.

Sneaker waves most commonly occur in northern California, Oregon, and Washington.

Watch: Moonstone Beach Sneaker Wave