New efforts are under way to convince government to salvage a massive quantity of oil trapped inside a shipwreck in one of New Zealand's most treasured marine environments.
If successful, it will be a return to the wreck which sank in 1940 with half a billion dollars worth of gold on board.
The gold has been removed but the RMS Niagara remains, sitting 120 metres below the surface with at least 1000 tonnes of oil still on board.
That's more than three times the 300 tonnes MV Rena spilled across beaches and reefs around Tauranga in 2011.
Records examined by the Herald show there are reports of small discharges of oil over decades with some observers recording oil stretching for kilometres on the surface of the sea around wreck.
While Maritime NZ considers the Niagara to be at no immediate risk of a massive oil spill, documents released through the Official Information Act show a new plan specifically for the Niagara was developed in 2016.
Auckland councillor Mike Lee wants the oil out as soon as possible, once an exploratory mission has been carried out to check the state of the wreck and to estimate how much is actually aboard.
"The real concern is as the wreck's got older and older, the bulkheads tend to collapse in on themselves. The tanks holding this bunker oil are likely corrupt and a lot of oil will come up at once."
He has written to the new Conservation minister Eugenie Sage and Transport minister Phil Twyford to ask for their support.
First he wants the ministers to meet experts on deep-sea recovery, including, Keith Gordon, an expert on the Niagara who wrote "Deep Water Gold: the story of RMS Niagara – the quest for New Zealand's greatest shipwreck treasure".
Gordon said concern about the oil was first raised with officials 20 years ago and even though there had been surveys done it was still not known exactly how much oil remained aboard.
"It's always been out of sight, out of mind. The Rena has brought it to a lot of people's attention. The ship is on its side and is collapsing."
The depth had always been seen as a barrier but Gordon said modern technology made it achievable for a cost of around $6 million.
Responsibility for the wreck has been a juggle at times but currently rests with Maritime NZ. Auckland Council landed responsibility also when the supercity was created, with boundary changes planting the wreck squarely inside its zone.
Oddly, it always had been but a mistaken understanding of where it was had meant the Northland Regional Council had been in charge.
Maritime NZ safety manager Nigel Clifford said there was no planned monitoring of the wreck but it did receive regular reports.
"The wreck lies below one of New Zealand's busiest shipping routes and the occasional oil leaks coming from it are reported to Maritime NZ by the many vessels that use it."
A WWII message from the NZ Prime Minister to his Australian counterpart, urging secrecy about the gold.
The OIA documents from Maritime NZ show its concern over an oil spill is low, with sampling from 2008 showing the type of fuel would exist in a semi-solid state because of the temperature at that depth.
It meant it was unlikely to shift or discharge in great quantities.
If it did happen, then Maritime NZ's "New Zealand Marine Oil Spill Response Strategy" would kick into action, along with local supporting plans. That would see 20 depots of oil spill equipment around the country along with around the national response team, made up of 400 trained staff from councils, Massey University, and other organisations.
The Niagara was launched in 1912 as the "Titanic of the Pacific" and set out to ply its trade at ports from Australia and New Zealand to the United States and islands between.
The ocean-going passenger liner was blamed for decades as the ship to have brought the deadly influenza virus in 1918, probably because of the false rumour that passengers Prime Minister William Massey and his deputy Joseph Ward had rejected quarantine measures.
As it happened, the virus was already in New Zealand with dozens of ships arriving from Europe and the United States around the same time.
The Niagara was then relied on at a critical early point in World War II. With the bitterness of Dunkirk fresh to the British and Commonwealth war effort, the Niagara was loaded with gold to pay for supplies in the United States and weapons bound for the United Kingdom.
The war had crept closer than simply commanding New Zealand's gold and rifles. It had crept so close that there were now mines sewn in the sea off the coast of Whangarei.
They had been placed there just weeks prior to the Niagara's departure - 228 in total.
Having just left Auckland, the ship was fully-laden with gold, munitions, oil and passengers for a lengthy trip across the Pacific.
Its route took it directly through the minefield.
At 3.40am on June 19, the Niagara struck a mine. All 400 aboard abandoned ship in the 90 minutes before the Niagara slipped beneath the surface, eventually coming to rest 120 metres below.
With that, she became the first ship sunk by enemy action in the Pacific.
As Lee says: "The Germans, with that mine, scored a big hit taking out the gold and all our ammunition."
Documents held in Archives NZ show the loss of the gold was a war secret and the subject of high-level communication across the Commonwealth.
The success of the 1941 salvage operation of almost $500m in gold celebrated in a message to New Zealand government ministers.