Three companies have changed their pleas, in relation to the 2019 Whakaari White Island eruption.
Kahu NZ, Aerius, and Volcanic Air Safaris Limited pleaded guilty to amended charges, in the Environment Court, today.
The charges relate to health and safety failings, in the lead-up to the eruption, that killed 22 and injured another 25.
The amended charges said the companies failed to comply with a duty to ensure the health and safety of workers and tourists.
Judge Evangelos Thomas said the trial's landscape is now far different than it was yesterday
Judge Thomas noted that the pleas came on "the last working day before the start of the trial.
Sentencing is set for August.
The pleas mean six parties, including the Buttle brothers and its company Whakaari Management Limited, face trial.
Monday's proceedings will see, the case called, plus brief acknowledgments, from Ngāti Whatua.
But Judge Thomas said the trial proper will start on Tuesday when Worksafe gives their opening address.