Horrified holidaymakers watched a young man fall down a cliff onto rocks at a popular picnic spot.
A 20-year-old Coromandel man suffered multiple injuries at the old Wilson Cement Works in Warkworth on Saturday, prompting warnings about jumping there.
A witness said 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 30m onto rocks in front of about 150 picnickers.
Mike, who didn't want his last name used, said it seemed like the man was submerged for up to three minutes before he was retrieved by two onlookers and hauled on to an airbed.
It was up to 10 minutes before the man regained consciousness, he said.
"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 victim's girlfriend who he was staying with in Auckland while on holiday.
Mike said he often visits the popular cement works picnic spots and has spoken to others about jumpers risking their lives.
There was a rope swing at the spot but this was removed and trees were trimmed to discourage climbers.
But Mike said fit youngsters like Saturday's victim are 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 said 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 and was taken to Auckland City Hospital.
"Jumping into quarries is very dangerous," Brownson said.
"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."
Auckland Council parks team leader Chris Burgess urged people not to play at the clifftop.
He said there were warning signs on neighbouring land.
- Rodney Times