Police are considering an in-and-out option which would mean leaving some evidence behind.

A team of scientists and emergency service experts are currently "locked away" in Whakatāne trying to put together a plan to bring the bodies of the eight dead on Whakaari/White Island back to the mainland.

Deputy Commissioner Mike Clement told media on Thursday that it would take at least 15 minutes on foot once crews landed on the island to get to the point where the bodies were gathered.

A range of options were on the table, including an 'in and out' style mission - something he would consult victim's families on.

Given the time it would take to reach the deceased, along with the 40-60 per cent chance of another eruption, Clement said the decision to return to Whakaari/White Island would not be taken lightly.

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MONIQUE FORD/STUFF Deputy Commissioner Mike Clement told media on Thursday that it would take at least 15 minutes on foot once crews landed on the island to get to the point where the bodies were gathered.

One emergency staffer spoken with Stuff said crews were waiting on the ground - along with the staff on board the HMNZS Wellington - which is currently stationed off the island.

It is understood Fire and Emergency NZ have been flying a drone over the island and feeding back data to the command centre.

How many people - and from what organisations - would be part of the response was part of the ongoing conversations.

It has been confirmed that a Ngāti Awa tohunga will accompany the recovery team to the island to conduct the necessary cultural imperatives and provide spiritual support to the recovery team once the green light is given.

Details around what clothing would need to be worn was also in discussion, the staffer said.

Given the toxicity of the island, it is possible the remains could pose a risk to those who retrieve them.

One factor Clement is having to consider is whether attempts to gather evidence where the bodies lay is possible.

As part of the Disaster Victim Identification (DVI) process, it is common practice for police to photograph the deceased where they have fallen. Along with this, they also note where the bodies are geographically.

Each body - and body parts - is labelled with an individual DVI number. Given the nature of the explosion, it is possible that there are multiple body parts which need to be recovered, one emergency staffer told Stuff.

As Clement said, the role of establishing the identity of the victim does not fall at the feet of the police, but with the coroner.

The DVI process is a five-step exercise which begins at the scene with the unnamed deceased and ends – it is hoped – with the identification of that person and the return of their bodies to their family members.

In a mass-fatality event, all victims begin as unknown, unnamed people. There is no room for error in the DVI process. Even if someone is carrying a wallet with a photo ID with them more information needs to be gathered for the coroner to be satisfied.

"We will get no thanks whatsoever if we reach a situation where we aren't able to [establish] the identity," Clement said.

"We came to repatriate all of the deceased or their families and do so there is sufficient proof to prove the identity of the coroner."

However, Clement said he was willing to do a "trade off" in the process of collecting evidence from the scene if it meant recovering the remains any quicker.

This would involve an 'in and out' style scenario, but would mean possibly crucial evidence could be lost. Clement would consult victim's families on this option as it could mean that identification is not reached even if the body is recovered.

"...If you are the next of kin and we don't get an identification as a consequence of that process then they may not be happy, and I would understand that," Clement said.

Following the Christchurch earthquake, there were 44 bags of body parts which were unidentifiable. Some families who had received the majority of their loved ones' bodies did not want to get further parts periodically as they were identified.

If the bodies are recovered from the island then they will be flown back to Auckland Hospital where autopsies will take place.

Clement said the various risks assessments would be presented to him at midday, and he would make a decision on whether recovery could go ahead following that.