Horrified holidaymakers watched a young man plummet down a cliff on to rocks at a popular picnic spot on Saturday.
A 20-year-old Coromandel man suffered multiple injuries at the old Wilson Cement Works in Warkworth, prompting warnings about jumping there.
A witness says the man was going to jump out of a tree and down a cliff at the quarry lake near the Mahurangi River but fell when a branch broke.
He estimates the man fell about 30 metres on to rocks in front of about 150 picnickers.
‘Mike' says it seemed like the man was submerged for up to three minutes before he was retrieved by two other onlookers who hauled him on to an airbed.
It was up to 10 minutes before the man regained consciousness, he says.
"It was horrific. I knew as soon as the tree branch broke it was going to be bad. I thought ‘he's either dead, or he's not coming up'.
"Children were crying and the whole place was cleared out in 15 minutes."
Mike called emergency services and comforted the family of the young man's girlfriend who he was staying with in Auckland while on holiday from the Coromandel.
Mike says it was an "accident waiting to happen".
He often visits the popular cement works picnic spots and has spoken to others about jumpers risking their safety.
There was a rope swing at the spot but this was removed and trees trimmed to discourage climbers.
But Mike says a fit youngster like Saturday's victim was still able to make it to the top.
The Westpac rescue helicopter landed at the quarry about 35 minutes after the fall. Auckland Rescue Helicopter Trust manager Greg Brownson says the man was unresponsive but breathing and was confused when he came to.
An ambulance arrived first at the scene and gave him pain relief.
The man had a laceration above his left eye, pain in the pelvis and right ankle and lacerations to his torso.
He was taken to Auckland Hospital.
"Jumping into quarries is very dangerous," Mr Brownson says.
"We've been to the quarry at Lake Pupuke several times over a few years and responded to many who have nearly drowned.
"Quarries like these are a known danger for swimmers.
"Fresh water is so different to salt water, it isn't as buoyant and people underestimate it," he says.
Auckland Council parks team leader Chris Burgess urges people not to play at the clifftop.
He says there are warning signs on neighbouring land, although the Rodney Times found only one sign saying "No access, private property" located near the tree.
- Rodney Times
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