New evidence reveals a Whakaari/White Island crater walk was cut short in the minutes leading up to last December's fatal explosion, as a guide noticed the situation was getting dangerous.
In audio released to Australia's 60 Minutes programme, an unnamed tour guide tells his group the island is at level two but nearing level three.
Survivor Stephanie Browitt told the programme her tour was then cut short. She lost her father and sister in the blast, suffered burns to 70 per cent of her body and has had 20 operations, with eight fingers amputated since.
She and other victims say they were left for dead and more lives could have been saved in the moments after the explosion as rescue helicopters were turned around.
Browitt, a 23-year-old Australian university graduate, stepped on to Whakaari on December 9 last year with her father Paul and sister Krystal.
The group, on a day excursion from Royal Caribbean's Ovation of the Seas cruise ship, say they were not forewarned of any threat of eruption on the island that day.
Footage and audio, released exclusively to Australia's 60 Minutes programme from Krystal Browitt's cellphone, reveal for the first time the voice of the family's unnamed tour guide pointing out the danger not long before the eruption.
"The higher the level the more risk there is of an eruption. Level three is an eruption," the tour guide is heard saying.
"Oh really," Krystal Browitt said.
"So we're on level two nearing level three now," the tour guide said, in the recording.
The last photo of the family shows the threesome posing, all smiles, in front of the island's crater.
But Browitt told 60 Minutes Australia just minutes after that picture, black smoke started to emerge.
"The first thing we did was take a photo, not realising that's an eruption and the danger, and only a few seconds later we heard the front tour guides yell 'run'."
Browitt said the guide had earlier cut short a part of the tour because gas emissions on the island looked too unusual.
Fellow Australian John Cozad also miraculously survived but lost his son Chris who died in hospital while John was in a coma.
"All of a sudden these hot crystals started hitting me in the forehead. They just got worse and worse. I remember saying to myself the Lord's Prayer because I just thought I was gone."
Surviving with his wife Lauren, Matt Urey said the blast quickly covered everything in sight.
"The visibility went to zero. I couldn't see my hand in front of my face and it was just hot. Everything was burning. I could feel my skin burning."
Wearing a full-face burns mask, Browitt told 60 Minutes she thought she was going to die.
"It was just rolling me over. The force was just that strong that my whole body was being shoved and pushed and rolled onto the ground and I was just hitting things whilst being burnt at the same time. It was the most terrifying moment of my life."
Matt and Lauren Urey managed to scramble aboard a boat, which took 90 minutes to get back to Whakatāne.
"That boat ride was agonising. We were burned horribly, we were laying in the sun being splashed with salt water and ice cold air while we were completely burned. It was excruciatingly painful," Matt Urey said.
Almost immediately after they saw the eruption from the mainland, helicopter pilots Jason Hill and Tom Storey got in the air and were among the first to arrive.
They were expecting paramedics to be not far behind them, but they ended up being the ones who saved people, including Stephanie Browitt.
The rescue helicopters were on the way, but were told to turn around.
St John's medical director Tony Smith told the programme the information they had at the time was that it was not safe to fly to the island and put their people on the ground, so they returned to Whakatāne.
They arrived on the island an hour later, but in hindsight he said they held off too long.
"We have reflected. Knowing what we know now we could have flown to the island earlier but had we got to the island sooner I'm absolutely medically confident that unfortunately we wouldn't have saved any more additional people," Smith said.
But Browitt told 60 Minutes if the rescue effort was quicker others like her father and sister might have survived.
"It's very upsetting just because I know it would have definitely made a difference for a lot of the people that were there, that were waiting, lives could have been saved that weren't that day."
Twenty-one people died, either on the day or in the weeks following. Two bodies have never been recovered from the island.
Another 26 were injured, most with long roads to recovery.
A WorkSafe investigation into the incident is ongoing.
The first anniversary of the eruption is next month.
- Checkpoint, RNZ