Eventually, she was able to scramble on to the rocks and out of the water, with assistance from family and bystanders.
Given the force of the waves, said Mr Larsen, she was lucky not to have sustained more serious injuries from being bashed against the rocks.
"She was very fortunate."
Mr Larsen said that particular stretch of rock has been the scene of many similar incidents where people have been caught by waves while out walking, and taken into the sea.
Such accidents, he said, happen "at least once or twice a year".
"It's not at all uncommon," he said.
"I've been called out to at least two or three other incidences at that reef with the helicopter.
"It's an interesting spot - there's something about the way the reef juts outwards into the sea. Even on a relatively calm day, there's lots of swells. The water hits the rocks hard, and catches people unawares.
He said he spoke with the woman once she was safe on land - and she said she was aware of the dangers of walking on the rocks.
"She was being reasonably careful. But she still managed to get caught."
He said the woman was "doing pretty well" by the time the helicopter arrived at the beach, after having been assisted by off-duty paramedics.
"The road ambulance crew had administered some pain relief, which helped her a lot," said Mr Larsen. "She was conscious and able to talk to us. She had about four family members gathered around her."
Once inside the helicopter, she was treated by Mr Larsen and a Wellington Free Ambulance paramedic.
Wellington Hospital was unable to confirm the woman's condition, but a hospital spokesperson said yesterday he believed she had been discharged.
