If the men hadn't raced to the aid of the 70-year-old she could have died, police say.
Engineer Chris Bayne, 53, was with his wife on his way to the physiotherapist for treatment on an injured arm when he spotted a cabbage tree had been knocked over.
"Straightaway I kind of knew that a vehicle or something had gone over [the bank], and I told my wife to stop the car," Mr Bayne said.
"I knew there was a creek and I could be going for a swim so I ripped my splint off [my arm] and went to the top. Just as I got there, there was another guy who was starting down the bank too."
That other guy was postman Sam Garlick, 38, who had also pulled over after seeing the damaged tree on the Dairy Flat Highway, on the North Shore.
"We scrambled down the bank and then we saw a car lying partly submerged on the side across the stream," said Mr Bayne, of Dairy Flat. "I waded in ... We could see [the woman] in the car and yelled to check if she was all right and asked repeatedly if there was anyone else in the car."
The four-wheel-drive had landed on its side in the stream about 10m below.
Mr Bayne - who injured his arm in a fall off a roof 18 months ago - turned off the car's ignition to avert a fire and kept talking to the elderly woman driver, who was starting to "doze off".
"Because of the angle of the car she was sort of upside down a bit, and the only thing that was stopping her from going in the water was her seat belt," said the Dairy Flat resident.
"She was starting to lose her grip on the doors ... so we were just holding onto her to keep her head out of the water."
Mr Garlick said he knew he "had to act" when, from the road, he spotted the car floating in the water.
"There was a truckie on the phone calling 911, and I yelled out, 'Come on, we've got to get down there.' It was quite a horrific scene."
When he and Mr Bayne reached the car, "we couldn't believe the lady was still OK. She was groggy but she was still OK. It's unbelievable.
"We had to make a decision whether we're gonna pull her out or not, but because of the instability of the car, we decided we were just going to leave her in there and support the car and wait for the fire crew."
Mr Garlick said they felt a sense of relief when a policeman arrived, who also jumped in and helped, followed by two firefighters.
"One of the firemen actually managed to rip open the back door and got in to hold her, and then I - because I was the littlest - climbed through her window ... and cut the seat belt and she was released."
The two firefighters, Mr Garlick and Mr Bayne then all pulled the woman out of the rear door.
"And she was all right. I mean, I was surprised," Mr Garlick said.
Senior Sergeant Matt Laurenson of Waitemata police said the men had done a "brilliant job".
The police were considering a way to formally recognise their efforts.
"The creek itself was down a very steep bank so for them to have both managed to run down there immediately was an impressive effort.
"The help they gave to the lady in the car was awesome and without their help it's quite possible that she could have died."
Fire Service spokesman Paul Radden said two fire crews from Albany and Takapuna were dispatched to rescue the woman. She was recovered from the vehicle about 30 minutes after the crash, which happened about 11am.
An ambulance spokeswoman said the driver had suffered serious injuries and was taken to Auckland City Hospital.
- NZ Herald
