"Me and a few others ran to the water but couldn't see anything. I ran out and felt a bit of a rip so I came back out and ran north along the beach for about 100m until I saw one of the girls ... I asked if she was alright and then she told me that she thought her friend was dead and still out in the water."
He swam out about 50m from the beach in the blustery conditions and found the missing woman, who he was told had drowned, lying face-down and unconscious in the water.
Another man came out to help him pull the woman back to shore.
"I lifted her and started to bring her into the beach," he said.
When he got her to the beach, Jackson started CPR.
"I was really scared. I just realised how serious the situation was, I'd never been in a situation like that before. It was really scary but I didn't really think I just sort of swam out further and tried to find her.
"She was breathing the whole time, but breathing really weakly, with water just pouring out of her mouth and nose every breath. She was unconscious the whole time."
He continued CPR until police helicopter staff arrived about 10 minutes later to take over, before the Westpac Auckland Rescue Helicopter team rushed the woman to hospital.
Jackson is in his third year as a lifesaver at Red Beach but had never found himself in a rescue situation like this one.
"I'd done all the training but I'd never had an actual situation like that before," Jackson said.
"The helicopters took her away and then everyone who was crowding around pretty much disbanded. Her sister was watching us ... she was crying and on the phone to [another family member]. Both of the girls were just in shock."
An Auckland City Hospital spokesman said the woman was still in a critical condition, in an intensive care unit, today.
Police said emergency services received several calls that two women had been swept out to sea near Piha's Lion Rock about 2.20pm.
The women had gone for a swim but conditions were "poor" with a king low tide and large waves, police said.
Officers from the police Eagle helicopter performed CPR on the 19-year-old woman for about 15 minutes after Jackson and an American tourist pulled her to shore.
She regained a pulse after a "considerable amount of time", police said, and was then flown to hospital.
Waitemata police district commander Superintendent Bill Searle said the efforts from the public, police and local lifesavers were to be commended.
"Sadly the young lady remains in a serious condition in Auckland Hospital and our thoughts are with her and her family.
"I'd like to thank everyone who was involved in yesterday's rescue, their actions have resulted in her revival at the scene and we now dearly hope she pulls through and makes a full recovery."
