The eruption on White Island caused death and dreadful injuries. But amid the fearful chaos, there was outstanding bravery. Here are three accounts from that horrific Monday afternoon.
Hamilton father Geoff Hopkins watched spellbound from a boat as White Island spewed steam, rock and ash thousands of metres into the air.
Moments later he was helping pull horrifically burned survivors from the water and providing live-saving first aid.
The 50-year-old now worries that those he helped are among the dead.
"They were just so massively burnt," he said.
Hopkins had been given the trip to Whakaari for his birthday by his daughter, who is a geology student. He believes they might have been the only Kiwis on their trip.
He heard gasps as the eruption sent a huge plume of white and grey smoke towards the heavens.
"At that moment, it was quite beautiful - we were watching a volcano erupt in front of our very eyes.
"But then the ash just rolled up over the rock face and as it rolled over, it just suddenly became quite menacing."
He saw people running into the sea to escape the ash and moments later boatload after boatload of survivors were pulled aboard and tended to on the deck.
Hopkins and others pour cold water on the victims' scalded skin and cut burned clothing away to help relieve their injuries.
Some drifted in and out of consciousness as he tried to tell them everything was alright.
"My fear now is that they didn't make it. There were five critical people on our boat and there's been five fatalities confirmed … they were just so badly burnt."
A local boat skipper has been hailed a true hero for his efforts in helping tourists escape the fatal explosion.
Paul Kingi was a skipper on the White Island Tours boat, working alongside his friend Hayden Marshall-Inman, who died in the explosion.
Details emerged of how Kingi put his own life in danger to save others.
In a post on the Pursuit Fishing Charters page, owner Rick Pollock detailed the dramatic incident.
He said Kingi - who'd worked with Pollock for five years - left the island "only minutes before the eruption".
When it happened he was "the first back on, rescuing and assisting numerous injured back onto the waiting boats".
"He went back again and again, ignoring the toxic environment and personal risk, until he was satisfied there were no more obvious survivors remaining," Pollock explained.
"This superhuman effort doesn't surprise me in the least as I've seen this fine man in action on numerous occasions, always controlling a bad situation.
"I'd like to recognise Paul for what he is on this occasion, nothing less than a hero."
San Francisco tourist Michael Schade and his family were among a tour group standing on the edge of the main crater 30 minutes before the eruption.
He took a photo of the steaming vent at 2.12pm - just a minute after the eruption began.
At 2.24pm he captured another image showing rescuers from White Island Tours scambling onto a jetty and helping people into a dinghy. The weighed-down vessel then headed to the main tour boat, a tour guide's arms around survivors.
Schade tweeted his "endless gratitude" to the tour crew for stepping up as first responders.
That boat ride back to the mainland - tending to those rescued - was "indescribable", Schade tweeted.
"[The] woman my mom tended to was in critical condition but seemed strong by the end," he wrote.
"The helicopters on the island looked destroyed."
He was "praying for them and their recovery".