The owners of Whakaari/White Island are challenging the criminal conviction of their company in the Auckland High Court.
The appeal hearing starts on Tuesday and is set down for three days.
Whakaari Management Limited (WML) and four other companies were fined and ordered to pay more than $10 million in reparations for health and safety failings in the lead-up to the 2019 disaster that killed 22 people.
WML itself was fined $1 million and ordered to pay $4.8 million in reparations to victims and their families.
Andrew, Peter and James Buttle - who own the island and are the directors of WML - filed the notice of appeal in March.
Their lawyer, James Cairney, said the finding that his clients' company had a safety duty to tourists visiting the island was "inconsistent" with what they thought.
"The fact that there was a duty hangs heavy on the family behind Whakaari Management. It hangs heavy because of the significant implications that there are from imposing a duty on a person essentially akin to a landowner granting rights of access to another person to conduct activities on their land," he said.
Cairney said his clients felt they were "wrongly charged" and had a right to test that.
In Judge Evangelos Thomas's decision following the trial last year, he said the company's failure to get risk assessments exposed others to risk of serious injury and death.
He said WML also consequently failed to install facilities that would mitigate the risk, and failed to ensure workers and tourists were supplied with appropriate personal protective equipment.
During the trial, the court heard WML was earning about $1 million a year from charging tour operators an annual licensing fee, as well as a fee for each individual visiting the island.
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