A huge wave crashed into spectators watching the Eddie Aikau Big Wave Invitational in Hawaii on 22 January, knocking them to the ground.
Footage shows a large group of people falling over as the water crashes around them in Waimea Bay.
"Onlookers got a touch of what can happen if you don’t back up and listen to the lifeguards," Honolulu Ocean Safety said.
The competition returned for the first time in seven years, and saw female and male surfers compete against each other for the first time in the event's history.
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