Onlookers have had to jump clear and run from car-sized rocks falling off the Skillion at Terrigal.
Tonnes of rock collapsed from the cliff-face yesterday afternoon, just metres from where people were standing.
The sudden collapse forced the temporary closure of the platform beneath The Skillion.
The area is busy with families during the school holiday period.
Central Coast Council has urged the community to stay away from the area, while they investigate.