Efforts to extract the cargo from the shipwreck of Port Kembla off Farewell Spit are underway.
The World War One era transport ship was sunk 17km off the coast of the South Island by a German mine in 1917.
The ship was carrying more than 1200 tonnes of lead from Australia for the war effort in Europe.
Deep sea diver Peter Mesley is one of the few people who have been down to the wreck.
In 2007 he and Simon Mitchell found the ship and removed the brass bell. He has been approached by the salvage team that is planning to extract the lead.
"The guys got in touch because historically we were the first guys ever to dive it," he said.
"They saw the footage and wanted to pick our brains for how the ship was lying."
While no salvage rights have yet been granted by the Transport Ministry or resource consents granted by the Tasman District Council, Port Kembla researcher Mike Fraser thinks that the permits are being sought prior to the 100th anniversary of the wreck, when it would become a historical site.
"Anything that happens has got to happen before it turns 100 years old," said Mr Fraser. "To get the salvage rights takes so long they might be going to get the rights to the lead in the hope that the price goes up."
Efforts to extract the lead in 1977 by Nelson-based company Nautilus turned into a "fiasco" when disputes about ownership stalled the project.
While the 1200 tonnes of lead are the main objective of the salvage operation, Mr Fraser said there could be other valuable cargo on board.
"In the court of inquiry, the skipper John Jacks drew up a diagram that says `400 tonnes bullion'. It could be argentiferous lead, which is lead with a huge silver content, in which case it's well and truly worth going for."
In addition to the potential for argentiferous lead, Mr Fraser said the normal lead would be sought after for electronics components because it had never been exposed to atmospheric radiation. All lead in circulation since 1945 has absorbed doses of radiation from tests of nuclear devices.
Mr Mesley said that any operation in 96 metres of water would be complicated and costly.
"Whatever happens it's not going to be easy," he said. "We'd do 30 minutes bottom time and we would be in the water for 3 1/2 hours because of decompression."
Mr Mesley and the other team members used a mix of gases called nitrox to offset the dangers of the deep dive.
Given the complications, Mr Mesley suspected that a salvage operation would need a small submersible craft.
- © Fairfax NZ News
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