The question has resurfaced over whether oil in the tanks of a sunken ocean liner off Northland's coast pose a big environmental risk.
Every couple of years local maritime watchdogs and conservationists raise their concerns over how much there is and the condition of fuel in the RMS Niagara.
The Auckland Conservation Board and its Northland counterpart have now voiced their concerns and intend writing to Government ministers asking for a conclusive survey to be done on the Niagara's corroding body.
The luxury cruise liner was sunk in 1940 by one of string of mines laid by the German cruiser Orion across the entrance to the Hauraki Gulf.
It lies at about 120m, between the Mokohinau and Hen and Chicken Islands, just inside the Auckland coastal marine area but also under the watch of Northland Regional Council (NRC).
Underwater explorers and writers Keith Gordon, Wade Doak and others have regularly stated thousands of litres of oil could still be in the degrading tanks due to rupture at any time.
Mr Gordon believed it was a case of "when", not "if", the remaining oil would be released.
The "time bomb" and "colossal black tide" scenario had also been written about by Mr Doak over many years.
Assessments and visual surveys of the wreck were carried out in 2000, 2008 and 2016.
The Advocate has written many articles about the Niagara and in August last year reported Auckland councillor and former Auckland Regional Council chairman Mike Lee's concerns the wreck was an "environmental time bomb capable of causing a disaster worse than the Rena oil spill".
"The environmental consequences of a Niagara bulkhead breakdown could be catastrophic. The damage to the Poor Knights Islands could be devastating," Mr Lee said.
Following the Niagara's sinking, and again two years later when a salvage operation blew holes in the hull, a thick blanket of oil coated the nearest shorelines and oil slicks up to 15km long were reported in the area as late as 2007.
The Niagara's tanks could have held more than 4000 tonnes of oil on its way from Auckland to the United States with a shipment of gold bullion. Some estimates hold that half the fuel could still be on board.
The Rena, wrecked on the Astrolabe reef in the Bay of Plenty in 2011, released only 350 tonnes of oil - with catastrophic results for the coast and wildlife.
A Maritime New Zealand (MNZ) spokesman said globules of oil had occasionally been reported rising from the Niagara but there had been no sign of ecological damage.
MNZ said any remaining oil would be in a semisolid state.
NRC harbourmaster Jim Lyle also said the oil posed a "low environmental risk" as it had all either surfaced already or solidified in the cold water.
Most of the gold has been recovered.