Volcano experts warn White Island was a "disaster waiting to happen" and "too dangerous" to visit.
There has been increasing anger people were allowed on the island despite warnings in recent weeks of increased volcanic activity.
Tragically, it erupted on Monday, leaving five people confirmed dead. Eight are still missing and 31 remain in hospital - the majority of those have critical injuries and the death toll is likely to rise.
"White Island has been a disaster waiting to happen for many years. Having visited it twice, I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter," says Emeritus Professor Ray Cas, from the School of Earth, Atmosphere and Environment at Monash University.
And Dr Jessica Johnson, lecturer in Geophysics at the University of East Anglia, UK, says the eruption was "unfortunate but not completely unexpected".
"Levels of activity at White Island/Whakaari have been relatively high since September, and even more elevated over the last couple of weeks, with increased numbers of small earthquakes and more volcanic gas detected than usual," she says.
"It is very difficult to say whether there will be more eruptions like this one, but GeoNet (part of GNS Science) are closely monitoring the situation and will communicate any changes in activity to the authorities."
Speaking to The AM Show on Tuesday, Prime Minister Jacinda Ardern said there will "absolutely" be an inquiry into what happened.
"Questions will need to be answered, obviously," Ardern said.
On November 18, GNS raised the volcanic alert on White Island to level 2, due to heightened volcanic unrest. It has responded to questions as to why tourists were allowed on White Island, saying it has "no jurisdiction over access to the island".
The chair of Ngāti Awa Holdings, which owns White Island Tours, told Radio New Zealand that the warnings in recent weeks "didn't meet its threshold for stopping operations".
"GNS do the monitoring, and they advise us if there are any changes, and we operate around their guidelines in terms of what levels are stipulated," Paul Quinn said.
"Level 3 and above we liaise more directly with GNS but that level 2 is still within our operational guidelines."
However the mother of an American woman who suffered severe burns in the White Island eruption told The Washington Post she was "just livid" tourists were allowed on White Island.
Barbara Barham's daughter, Lauren Urey and son-in-law Matthew suffered severe burns as a result.
"There's been warnings about it...My son-in-law never would have booked the excursion if he knew there was any chance of them being injured," she said.
