The lawyer for the owners of Whakaari/White Island is calling for an independent public inquiry into the deadly eruption, saying government agencies, including WorkSafe, should be held accountable.
Five companies, including that of the island's owners, have been fined and ordered to pay millions of dollars in compensation for failings leading up to the disaster.
A coronial inquiry into the 2019 eruption, which killed 22 people, is still to come.
But lawyer James Cairney wants a Royal Commission to investigate the broader picture - including the role of multiple government officials.
"It screams out that this has to occur. There has to be a formal inquiry into what happened, a commission of inquiry, with a broad scope and a particular focus on the various government stakeholders and decisions that were made."
Cairney said multiple government agencies were involved in Whakaari's operation as a tourist destination and in the search and rescue operation after the eruption.
"In a case of the magnitude of this, I think there needs to be a point of criticism of a variety of government bodies, a point of criticism of legislative framework around how this operates."
Mark Inman's brother Hayden Marshall-Inman was a Whakaari guide and the first person confirmed dead in the eruption.
He supports the call for a public inquiry.
"WorkSafe are responsible, or at least should be held to account for some part of the actions, because a lot of the companies involved relied heavily on WorkSafe's advice around health and safety and how they accessed the island."
Inman said it was not about finding blame but about getting things right in adventure tourism.
"What you want as a New Zealander is to know that you're safe in your workplace, in what you're doing, and have the reassurance that if WorkSafe have signed off on something, that you feel comfortable that you mitigated all risk," he said.
"Moving forward as a nation we need to be comfortable in our compliance around our adventure-based tourism."
Department of Internal Affairs documents show that within a month of the tragedy, it gave advice to the then-minister about the possibility of an inquiry.
The government then indicated that it would not make any decision until both the WorkSafe and coronial investigations were finished.
In 2020, the National Party called for a commission of inquiry saying criminal proceedings would be too narrow given the magnitude of the disaster.
But the Minister for Workplace Relations and Safety, Brooke van Velden, said a royal commission was not needed.
"I would expect the appropriate next step would be a coronial inquest rather than a royal commission."
She said no request for an inquiry had passed her desk.
"WorkSafe has done the appropriate steps, which is to look into the investigation, to take those people who they believe had shortcomings to court and businesses have been prosecuted and that's definitely been the right thing to do."
Inman questioned why the government did not see the need for an inquiry.
"Is it government protecting government agencies? That's probably the best way to describe that."
The Ministry of Justice said a royal commission would need to happen before a coronial inquiry, for which a date still has to be set.
WorkSafe says it is 'committed to learning and to improving safety systems'
In response to questions from RNZ, a WorkSafe spokesperson said that if a Royal Commission were to go ahead the agency could potentially be a focus, and so "it does not have an opinion on whether one should be held".
"WorkSafe is committed to learning from the eruption and improving the systems to keep people safe," they said.
"Since the eruption a large amount of work has been carried out to ensure the Adventure Activities regime is robust."
The agency has been the focus of multiple independent reviews in recent years, including one focusing on its role in relation to Whakaari/White Island.
And a review of the regulation of adventure activities (released in 2020), found WorkSafe should improve its monitoring and enforcement, and that more safety improvements could be made.
"WorkSafe also carried out work to ensure any lessons to be learned were, and improvements made," the agency's spokesperson told RNZ.
"One example of all this work is the strengthening of Adventure Activities regulations, and WorkSafe's role, which takes effect from April 2024."
The WorkSafe investigation into the eruption and the events leading up to it led to it charging 13 parties.
The trial led to the conviction of one company, guilty pleas from six parties, and charges against six other parties being dismissed.
"WorkSafe's role was explored during the trial. WorkSafe accepts the comments of Judge Thomas within the context of the sentencing outcome. It is not appropriate to go into any further depth ahead of an expected Coronial Inquest," the spokesperson said.