Police say the plan to recover the bodies from Whakaari / White Island tomorrow morning will take several hours, and still carries a lot of risk.
Watch Deputy Commissioner Mike Clement's full media briefing:
Shortly after first light tomorrow, NZ Defence Force assets with specialised equipment will go on to the island and make every effort to recover the bodies, Deputy Commissioner Mike Clement said.
Eight people are confirmed dead after the eruption on the island on Monday, and another eight are missing, presumed dead.
Police have not yet returned to the island to retrieve any bodies there as it has been deemed too dangerous.
At the same time, the risks have increased, with GNS Science late morning raising its forecast likelihood of a major eruption from 40-50 percent, to 50-60 percent in the next 24 hours.
Clement told media in Whakatāne this evening that it was still a risky operation and police had to be very cautious.
"A lot has to go right for this to work."
Photo: RNZ / Dom Thomas
Clement said the best option was to get on to the island, get the bodies and get off as quickly as possible, but added that he expected it to take several hours.
He said there had been an "incredible effort" to put the recovery operation together.
The missing victims' families have been briefed on the operation.
He said he expected the mission it to take several hours, "the balance of the morning" and police did not expect anything to change overnight in terms of risk.
"The risk has not gone," he said.
"My feelings are ... we're here to do a job, we understand the expectation from everybody. I hope you understand from our perspective the need to do this safely."
Those going on the mission were not only volunteers.
The police boat Deodar III arrives into Whakatāne. Photo: AFP
"People volunteer when they put uniforms on, and they develop their skills and in this case incredible skill. In a disciplined organisation like NZDF they are fronting up to do what they are paid to do, what they are dedicated to doing and I'm incredibly proud of them and have huge respect for them as you will, I have no doubt."
He said they had built in lots of opportunity to bail out of the plan, should things not go the way they want.
"We have planned for an eruption."
He said GNS scientists would be part of the team, not going on to the island but going out on the HMNZS Wellington ship to provide analysis and support.
As well as the ship, there would be helicopters involved and specialist staff. He said the technical decisions on the ground would belong to the New Zealand Defence Force, and their plans had been designed to change depending on circumstances.
He said the monitoring they had done showed what appeared to be six bodies, and they would look for the other two people missing but they would not be the priority.
"We know through the eyewitness interviews that we've done of the groups that were there on the island immediately after the eruption and the drone footage and the other footage that we've got access to that we can see... six bodies. But we know that we are missing eight people.
"Our first priority will be to get those six people off, and we will have very limited opportunity to look for the two others that we suspect are out there somewhere.
"We can't find anything more than six. It's not to say they aren't there but we can't find anything more than six. That's as good as I can get it at the moment."
Whakaari / White Island in the hours after the eruption. Photo: RNZ / Dom Thomas
He said plans would change if the volcano erupted again.
"We'll be coming back to the table if there's an eruption tonight."
Earlier today, Clement said he would only send people in when he thought the risks could be mitigated.
Volcanic activity is steadily increasing.
GNS Science this afternoon increased its predicted threat of an even bigger eruption at Whakaari / White Island in the next 24 hours.
The monitoring agency had forecasted a 40 to 60 per cent chance, but today increased this to a 50 to 60 percent chance.
The alert level remains at 2, but scientists said there was still a risk of eruption and it was not safe to launch a recovery eruption.
GNS said there had been an uptick in seismic activity since Monday's eruption, which killed at least eight people and injured dozens more.