GNS Science says, in hindsight, the bodies on White Island could have been recovered on Tuesday.
Increased volcanic activity on Monday meant there was no opportunity to land and retrieve the bodies.
The delay is angering families and the local community some of who believe police are dragging their feet.
One of the pilots who flew to the island to rescue people after the eruption on Monday is furious he's not able to return to retrieve those who weren't so lucky.
"The conditions are perfect. They were yesterday, today, so I don't understand why they wouldn't go - I'd go," Mark Law told Newshub.
An expert volcanologist says the conditions were good enough for a rescue mission.
"They could have gone out yesterday and got away with it," said GNS volcanologist Brad Scott.
On Tuesday, GNS put the risk of another eruption at 50-50, but it turned out to be relatively calm on the island.
"It takes 20 minutes to get out there. We know where they are. We could land and bring them home," said Law.
He says if it was up to him - he would've been there and back before lunch.
"It's just a matter of putting them in a bag, putting them in a helicopter and bringing them home."
But police say it's up to experts to give them the information they need to make the final decision to go or not. They're simply not prepared to risk lives to recover bodies.
"We cannot put other people in jeopardy until we're absolutely certain it is safe," said acting assistant commissioner Bruce Bird.
There were perfect flying conditions on Monday, but since 4am on Tuesday, there's been significantly more volcanic activity and no attempt to get onto the island has been made.
