While the United Nations' International Seabed Authority (ISA) in charge of issuing mineral exploration licences has granted 26 so far, Papua New Guinea remains the only country to have granted an operating permit for ocean floor mining.
Canada's Nautilus is on track to start operations at its Solwara gold, copper and silver project in the Bismarck sea off PNG in early 2019, making it the first undersea mine on the planet.
A Russia K-129 submarine had sunk 1,500 miles north-west of HawaiiBut modern-day seabed mining has a strange history.
An extraordinary BBC report details how in 1974, US spies launched an operation to salvage a Soviet submarine carrying nuclear missiles under the guise of a Howard Hughes-financed seabed manganese mine.
A Russia K-129 submarine had sunk 1,500 miles north-west of Hawaii and the CIA devised an elaborate plot dubbed Project Azorian to recover the vessel without alerting Russia about their intentions.
The cost was $500 million, a staggering amount at the time, and the plot was so detailed that it even sparked a frenzy in the stock of purported undersea mining companies that appeared in the wake of the Hughes endeavour.
Read the whole story here