A council worker clearing bins was alerted to his location by Mr Keys' dog.
Hauraki District Council worker Bruce Mackenzie was on his normal routine emptying rubbish bins and, as he pulled into the carpark, he noticed a dog jumping around in the far corner.
Mr Mackenzie parked alongside the bin beside the playground, emptied it, got back in his truck and was about to leave but the dog was still jumping up and down. He drove over to the corner of the carpark and his headlights caught something shiny.
"I realised it was a person. I called out 'hey mate are you all right'. He said 'help me, help me'.
"The dog is still jumping all around but I squatted down and his next words were 'roll me over, roll me over'. I said, 'I can't do that mate, I'm calling an ambulance'.
"He was talking - so was breathing. He wasn't bleeding but he was lying on top of his bike, across the hole - he looked awkward.
"I just refused to move him, just kept reassuring him that help was on the way."
When St John arrived, they called for back-up and the Waihi Volunteer Fire Brigade arrived not long after.
Mr Keys was transferred to Paeroa by road before being flown to Middlemore Hospital.
Mr Keys' sister, Fiona, was grieving with her family yesterday as they wondered how he would come to terms with a life without the use of his body.
Doctors had told her the accident had left her brother a quadriplegic, she said.
He had always been a lover of the outdoors, a keen hunter and fisher on weekends, a spray contractor during the week and would ride his bike after work to exercise his hunting dogs.
"It's appalling that he won't come waltzing back in here ... it's just torturous to know he'll be trapped in that body forever," she said.
He was taking his dog for a run the night of the accident, as he did every other night after work, she said.
She believed it was the close relationship he had with all his dogs that made Bailey stay by his side through the night.
Bailey is now living with Fiona at her Whakamarama home, adjusting to life without her owner.
"She's having a lifestyle change too."
The whole family was devastated for Mr Keys and understood an existing cordon around the sink hole had been removed before the accident.
"We're gutted. We're especially gutted if it was preventable."
Fiona's daughter, Amber, Mr Keys' niece, said it would be a difficult reality for her uncle to come to terms with.
"He's very outdoorsy, loves hunting, loves fishing in the weekend. He's a happy go lucky kind of guy, doesn't like to sit down or be stuck inside.
"It's gonna be hard for him to come to terms with not even being able to scratch his own nose ... He's never been one to ask for help.
"But he's still in the stage where he's just grateful to be alive."
Ian Keys said the family had been at the hospital with his brother who had just undergone three hours of surgery to secure his neck and the doctors had told the family he had serious damage to his spinal cord and, at this stage, was paralysed from the neck down.
"It's a shock for the whole family. His daughter is with him."
He said Mr Keys had relayed the story of what had happened to him.
"There was a bare open hole ... I guess in the dim light he didn't even see it. He just rode into it.
"He said he had no idea what had happened ... next thing he was flying over his handlebars and he heard his neck break when he hit the ground."
Mr Keys could not move.
"He knew that he was in trouble when he couldn't get off the bike. He couldn't move, he couldn't do anything," said Ian Keys.
Plastic barricades have been erected around the sinkhole since the accident, but it has not yet been filled in, Hauraki District Council chief executive Langley Cavers said.
The incident had occurred in a part of the reserve, close to a car parking area, which was prone to subsidence.