The leader of the body recovery mission on Whakaari / White Island has opened up on the perils his crack military squad faced, including how dangers associated with heat and fatigue forced the team to temporarily halt part-way through.
And the top military operator has revealed that they were warned there was a 50-60 per cent chance the volcano would erupt again during their dangerous mission.
Twenty-two people died from their injuries – including 20 tourists and two tour guides -suffered when the tourism destination erupted underneath then on December 9, 2019.
WorkSafe NZ has laid criminal charges against 10 organisations and three individuals following the disaster.
While the majority of the people who were on the island at the time of tragedy were rushed off the island by White Island Tours vessels and private helicopters which had flown to the scene, eight bodies remained.
Four days after the eruption, a crack team of New Zealand Defence Force explosive ordnance disposal (EOD) operators landed on the island, putting their own lives at risk to try and recover the bodies.
The eight strong team – made up of six men and two women – were a mixture of NZDF medics and bomb disposal operators who specialised in chemical, radiological and biological devices.
What they encountered on White Island were searing temperatures, with the hostile environment featuring toxic and acidic gasses and the ever-present risk of another eruption.
In a bid to reduce risk to themselves, the EOD team were kitted out in several layers of protective clothing.
But the multiple layers also made for a "really hot environment to operate in", the team leader told the New Zealand Herald.
"Parts of the island were easy going," Captain C – who can not be fully identified due to his role in the NZDF - said. "Other parts were really wet and sludgy.
"In terms of the stream we had to move through for a search, that was boiling so that increased the heat. The added fact was the rebreathing apparatus was heating up and effectively raising your internal body temperature. So all of those factors combined to make it a really hard, fatiguing task.
"The team knew it would be physically hard task, but they didn't anticipate just quite how hard it would be. And at one point the team told me they actually needed to stop. They couldn't keep going.
"It was the point of too much fatigue, it was too dangerous."
The team was brought back down to the shoreline, where they carried out a decontamination process, while resting and rehydrating.
"It was a decision to balance the team's physical ability to do the task and the time we had and I think in the end we made the right decision," Captain C said.
The team were wearing four separate layers of protective uniforms; including a suit each to protect against hazardous vapour, and another to protect against the acid-rich environment after eruption.
"For breathing apparatus, each person had rebreathers, which effectively provided long-duration air supply to those on the ground," Captain C said.
"This allowed for a limited time window on the island for the team to successfully complete their task and get themselves off the island in time.
"With all of the equipment on, it made for a really hot environment to operate in."
Captain C revealed when he first heard about the eruption he had been at his children's swimming lessons.
It wasn't long before he was questioning himself on whether he would be called upon to help.
"Volcanoes were never an environment we had experience with, but the wide variety of our training meant we were best placed to take on the task," he said.
Previous events the team had handled were being deployed to Japan to support the urban search and rescue task force after 2011 Fukushima tsunami which killed more than 15,000 people.
Closer to home, the unit was also involved in the search and rescue operation at the CTV Building after the 2011 Christchurch earthquake.
"But Whakaari was different. We were very aware of the risk the environment posed to us through the regular updates we received from GNS.
"In order to achieve the mission, we had to focus on the task at hand."
The elite squad travelled to near the shoreline of White Island via HMNZS Wellington. They then boarded smaller landing craft to get onto the disaster zone.
"The sea was calm, we were focused, and grey ash continued to bellow from the crater.
"We're used to working in this type of protective equipment, we're used to the gas detection equipment and all those things that keep us safe in a hazardous condition like that. This was well within our scope of training and abilities, and although certainly at the extreme end of what we do, it's what we are trained to do.
"We were told it was still in an active state, effectively. And that it could erupt at any time during that period. The stats we had for that Friday that we went on was about a 50-60 percent chance of eruption.
"An eruption was definitely in the back of our minds, and definitely once we were on the island, it was in the forefront of a lot of the peoples' minds."
While on the island, a "sentry" was entrusted to watch the crater lake and watch out for any signs that an eruption was pending. Warnings were also being provided by GNS Science.
"We also had actions we could take like taking cover, sheltering during those first signs of eruption, and then making our way back down to the water. So there were steps in place to keep up as safe as we could be."
The goal throughout the mission was to reunite the bodies of those who died with their loved ones.
The unit ultimately located six bodies which were later formally identified and returned to their families. The remains of hero tour guide Hayden Marshall-Inman and teenaged tourist Winona Langford were never recovered.
"We got a letter from one of the victim's families so that was really cool to get and it was definitely a pretty heartfelt thank you so that was definitely appreciated," Captain C said.
"We did everything that was asked of us in the time that was asked, and I'm really proud of the team and what they did."
He added when the team was later leaving the area of White Island they could hear a "low rumble" coming from it.
"It's hard to explain, you knew something was happening," he said.
"Once we were on the boats, we looked back on the island and thought we did exactly what we were asked to do. It was pretty surreal.
"This is something that I can look back on now with a bit of pride that I managed to do and achieve it. I think a lot of the team has that view as well. Although a fairly challenging task, we did what we had to do."