Work has started on a new safety fence at Wedding Cake Rock in the Royal National Park to reduce the chances of people dying for a selfie.
A geotechnical survey shows the Wedding Cake Rock sandstone feature is highly unstable and could collapse into the ocean below at any time.
"The new fence is being installed to improve safety for visitors to Wedding Cake Rock," National Parks and Wildlife Service (NPWS) area manager Shaun Elwood said.
"Unfortunately, some people chose to disobey the warning signs and climb over the old fence to take selfies for social media and we have been forced to take further action.
"The better barrier will be made of high-grade stainless steel with an inward tilt to make it harder for people to climb."
New safety signs will also inform visitors of the area of the imminent danger of the rock collapsing.
"We are urging people thinking about trying to climb the fence to consider carefully the consequences of their actions,"Mr Elwood said.
"This includes impact an accident would have on their family, loved ones and friends.
"People should also spare a thought for our staff and the emergency services people who put their lives at risk to undertake dangerous rescues and retrievals should something go wrong."
In July last year, NPWS expressed frustration and concern over continued risk-taking by many Wedding Cake Rock visitors.
The re-appeal for visitors to stop risking their lives for the sake of a selfie came after drone video footage showed about 20 people inside the fence, several of whom had their legs dangling over the edge of the rock.
