The man was walking to the fishing spot, down a "well-trodden path", when he slipped and fell at a particularly narrow and slippery section of the track, Peter Legg, station officer at Kawakawa Bay Volunteer Fire Brigade, said. His fishing tackle and bait could be seen in the grass where he lost footing.
There was no railing at the section where the man fell, Mr Legg said.
"There was a fisherman already down there, and he went off for a wander to stretch his legs, and he found the guy. So he could have been there for a little while."
Mr Legg added: "He went off for a walk and heard him, more than saw him."
The man was not a local, Mr Legg said, describing him as of Asian descent and aged between 45 and 50.
Another fisherman in a kayak also saw the commotion.
Local emergency services were soon on the scene, and the Westpac Rescue Helicopter was also called to help reach the man.
"They dropped the paramedic off and he, along with ambulance people and our local first response, tended to him," Mr Legg, who was the lead firefighter on the operation, said.
"We put him in a sling and carried him out to a point where the chopper could come and winch him off, and they took him around to what we call Waititi Bay, which you can actually see from where he fell, and got him into the back of the helicopter and away they went."
He was "a lucky man", Mr Legg said.
Despite the lack of railing and slippery nature of the path, Mr Legg said: "We don't get a lot falling over there.
"But it's one of those things where I suppose if you look out to sea or something you'd probably miss where you're supposed to go, which is easy because there's a lovely view from there."
Earlier one local, who did not want to be named, said the man fell from a path at Snake Gully when the railing gave way.
"[It's] a big fall, a very big fall," he said.
Getting access to the man's location was "really difficult", Scott Osmond of the Fire Service northern communications centre said, and the Westpac Rescue Helicopter was called in to help.
Simon Owen, Auckland Westpac Rescue Helicopter co-pilot, said the chopper arrived at the scene around 11am, after "kayakers cruising past found him and raised the alarm".
The 57-year-old man had fallen approximately 15m, Mr Owen said.
The man had multiple lacerations and a number of suspected fractures, he said. He was conscious and "in a fair amount of pain".
However, it was not known when or how he fell because he was alone, and did not speak English, Mr Owen said.
"[He's] lucky the kayakers found him and lucky we could get in and get him out fast."
Pukekohe resident John Longson was in the area early this morning to watch the sun rise.
A keen drone photographer and videographer, Mr Longson captured some footage of the area believed to be close to where the man fell.
He spoke to a fisherman, he said, who was asking for local information on good fishing spots.
It was a dangerous area, Mr Longson said: "You could quite easily fall about 8m into the water, it's quite a drop."
There were no barriers or rails for protection.
"I was doing a live feed and I was walking down the cliff face, if you will, and it was a little bit dangerous so I stopped doing that."
The man was then winched to safety by the rescue chopper and flown to Middlemore Hospital in a serious condition.
A spokeswoman for Middlemore Hospital said the man was now stable.
