Visitors at Sydney's Royal National Park got more than rockpools to paddle in when a freak wave swept through the pools injuring several people.

People filming the scene from higher up captured the moment. A man can be heard yelling "brace yourselves!"

About 100 people were hit by the wave as a wall of white water swept through the pools.

Three woman were airlifted to hospital, one suffering head injuries, but all have been discharged.