WWII shipwreck 'still bleeding oil'

A time bomb lies off Northland's coast, says Keith Gordon, pictured in 2008 with the bell recovered from the Niagara the year before. Photo / John Stone

The wreck of a ship sunk off the Northland coast 75 years ago poses as big an environmental threat as the Rena, according to underwater pioneer Keith Gordon.

Mr Gordon said the RMS Niagara lying on its side in 120m of water, in the main shipping channel between the Hen and Chickens and the Mokohinau Islands, could hold a store of oil that "is an ecological time bomb".

The Niagara sank in 1940, with no loss of crew or any of its 349 passengers, when it hit one of several German mines strung across the Hauraki Gulf entrance. The luxury ocean liner, built in 1912, was carrying 4200 tons of oil fuel on her voyage from Sydney to the US, via Auckland. It was mined the day after leaving Auckland, and was the first Pacific shipping casualty of World War II.

Oil has been seeping from the wreck of the Niagara for decades, with this file photo taken in 2000.

Over a long period following the sinking there were reports of oil slicks 15km long, stemming from the wreck's location.

"Her sinking caused a huge amount of environmental and ecological damage, up and down this coast and over to Coromandel, far more damage than the Rena caused," Mr Gordon said. "But being wartime, it wasn't recorded in detail."

What was recorded then and has always been the big story told about the Niagara is the 8.5 tons of gold being taken to the US to pay for British munitions. Most of the gold was retrieved in 1941, when salvagers blew holes in the hull to access the holds.

Since then, there have been many reported sightings of oil on the water's surface, with no proven cause. Mr Gordon estimates there could still be 1000 tons of oil in tanks which an old sonar survey and remote controlled filming indicate are still intact. "But how long will that tankage stay intact?"

Despite efforts by the New Zealand Underwater Heritage Group to convince authorities of the need, there has been no survey to determine how much fuel the wreck still holds.

"At 120m, it's too deep, it's out of sight and out of mind."

Mr Gordon said the authorities claimed oil that surfaces occasionally was from two vehicles being carried on the Niagara.

"We know it's bunker oil that's coming up, we've taken samples."

Mr Gordon is the inventor of a remotely operated vehicle (ROV) that has been sent down to film the wreck several times. The footage shows icicle-shaped rusticles on the hull, indicating the steel is changing structure as the iron in it oxidises. Mr Gordon said that destabilisation of the steel adds urgency to the need for a survey.