The real lesson to be learnt from the fire that destroyed a tourist boat off Whakatane may be how all 60 people aboard survived, authorities say.
The 53 passengers and seven crew that were on board the PeeJay V when it caught alight had to jump into the sea to be rescued.
Transport Accident Investigation Commission (TAIC) spokesman Peter Northcote said the fire was very intense, so establishing the initial source of ignition might be difficult.
He said investigators would look at the way the crew were prepared to respond to an accident and the equipment available, among other things.
"So it all started pretty quickly, obviously it started int the engine room but we don't know yet what started it, and there'll be a thorough investigation into that.
"At this stage we are just dealing with the fact that we've got all our passengers back, we need to concentrate on looking after them."
Mr Northcote said it would be some time before they decided whether they needed to try to bring the vessel up, or dive down to examine it.
White Island Tours is now operating again. The company said it has received the usual number of bookings for this time of year.
Managing director Peter Tait said more than 40 passengers went out this morning and 40 more will go this afternoon on one of its two remaining boats.
He said there had not been any safety concerns from passengers but they had received a lot of enquiries from overseas wholesalers.
Mr Tait said it was shaping up to be a profitable summer before the fire.
Question mark over wreck
TAIC lead investigator Rob Thompson said they would soon decide what to do with the wreck.
"It really depends on what questions we have to answer, and what value we could get out the wreck," he said.
"Fairly shortly, we'll have to decide. Obviously, if we were to salvage it, the sooner you salvage it the better."
Mr Thompson said TAIC should have all the critical evidence within the next few weeks but the full investigation would take much longer.
He said how long would depend on how many other investigations were going on but "we might look at something like 12 to 18 months".
There was no immediate evidence to suggest White Island Tours should not be operating, Mr Thompson said.
Salvage expert Dougal Fergus, from New Zealand Diving and Salvage, told RNZ retrieving the wreckage should be fairly straightforward.
However, Mr Fergus said there were questions about whether it would be worth the effort for the amount of information it could provide to investigators.
He said, in his experience, it was likely the fire was caused by either an electrical or fuel issue, and "a lot of the evidence will have been destroyed by the fire".
Luggage blocked exit - passenger
One passenger on board the ship said it was a terrifying experience - and there was luggage blocking an emergency exit.
Elaine Rogocki was visiting New Zealand from Essex, and was with her daughter at the time.
"They told me that I had to jump in before my daughter, because she can't swim and she needed help. So I did, and I jumped in and was taken to a boat that was there waiting, not realising that she hadn't come behind me yet.
"So while I was sitting on the boat, I was watching the boat, [which] was now on fire, and she hadn't got off because she can't swim."
She said eventually her daughter made it to the life raft.
However, she had another concern with a blocked safety exit.
"I was a little bit miffed when I was sitting down on the deck because one of the escape doors was closed and it had passenger luggage in front of it, which I thought was a hazard.
"Other than that, the crew did everything they could to help and were excellent in this case."