It's an industry that has divided Pacific Island nations and met pushback from environmentalists.
Deep-sea mining — heralded by some as a way to power the global shift to renewables — is heading towards a turning point.
The first application for a licence to mine the seabed of valuable metals used in batteries could be decided by the International Seabed Authority (ISA) later this year.
It's a scenario that has upped the stakes in a vote on Friday (Jamaica time) for the top job at the UN-affiliated organisation, which regulates deep-sea mining in international waters.
Nations opposing seabed mining fear the ISA could approve an application before internationally-agreed environmental rules and regulations are in place.
And whoever nations elect to lead the authority will have considerable influence in such a decision.
National representatives meeting in Kingston, Jamaica will choose between two candidates that offer different views of the industry's future.
The incumbent Michael Lodge, a British national and lawyer who has served two terms as the authority's secretary-general, has popular support among seabed mining companies.
His opponent, Leticia Carvahlo, is a Brazilian oceanographer and diplomat, pushing a more conservative regulatory approach than Mr Lodge.
She's promising that no decision on mining exploitation licences would be made before the ISA's decided on its regulations — but she says she's no opponent to the industry.
"I wouldn't step up to this function if I was against deep-sea mining," she said.
"I'm absolutely loyal to the law of the sea vision established 30 years ago."
In a speech to the UN in June, Mr Lodge said it was the ISA's "most important task" to complete the regulatory framework for deep-sea mining "in a timely and responsible manner".
The election was embroiled in controversy last month amid reports that Kiribati’s ambassador, whose country nominated Mr Lodge, suggested Ms Carvahlo take another ISA job to remove her from the race.
Kiribati defended its actions, and Mr Lodge was quoted in the New York Times denying any suggestion he tried to improperly influence the election.
The vote comes as supporters of the industry, environmental groups and Pacific Islanders debate the benefits and risks of-deep sea mining — and as mining companies explore the rich deposits of minerals on international seabeds.
'Picking up rocks'
Deep under the ocean's surface lies what's described as the world's largest resource of metals used in renewable technology like electric vehicle batteries.
Vast arrays of polymetallic nodules, accumulated over millions of years, contain nickel, copper, cobalt, and manganese — and deep-sea mining exploration companies are mapping them.
The Metals Company (TMC), based in Canada, wants to begin mining the seabed and developing the industry, which it projects could grow to billions of dollars in value.
But TMC chief executive Gerard Barron disagrees with the description "mining".
"I'd much rather have what we are, our activity, not described as mining, because in the true technical sense of the word, we're picking up rocks," he said.
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The nodules lie 4,000 metres below sea level on the ocean floor, but unlike minerals on land, they aren't buried.
"They literally lie on the ocean floor like golf balls on a driving range, and so the task of collecting them is really like collecting those golf balls," Mr Barron said.
"Our robot crawls along the sea floor, we actually fire a jet of water at them horizontally and that creates an inverse pressure, so it allows us to lift them."
But it is not just the ease in which these critical minerals can be "mined", it's the volume in which they exist which has TMC excited.
There's an estimated 19.1 billion tonnes of polymetallic nodules that exist in the Clarion-Clipperton Zone (CCZ), an area that spans 4.5 million square kilometres in the Pacific Ocean between Hawaii and Mexico, and the area where TMC has focused its operations.
"It's a very large resource, in fact if you think about the known reserves of nickel and cobalt and manganese, 70 per cent of all of our planet's known reserves are in this one deposit," Mr Barron said.
But critics say not enough research has been done into how deep-sea mining could impact the environment, with many fearing it could cause irreversible damage.
A scientific study also found that metallic deposits on the seabed are supplying the ocean with oxygen — adding to concerns that mining could harm the marine environment.
Deep-sea tensions
The International Seabed Authority is finalising environmental rules and regulations for deep-sea mining, and expects them to be in place later this year.
But Ms Carvalho is concerned that with Mr Lodge as secretary-general, the ISA will approve applications to mine the deep sea before the environmental rules are in place.
"How can a regulatory organisation approve mining requests without the rules and procedures fully developed?" she said.
"The only thing I can envisage if a mining request is approved without the full development of the rules, is a regulatory cacophony full of [multiple] litigation processes in different courts."
Since July 9, countries and private companies have legally been able to apply for provisional licences.
Mr Barron intends on lodging an application.
He expects the ISA will have established its regulations for mining by the time it decides on his company's application.
"We of course do have the legal right to lodge our application any time now," he said.
"Even if we were to lodge it before the rules are finally in place, we expect based on the published timeline from the International Seabed Authority, that by the time we were given our permit to move into the extraction phase that those regulations would be locked down and in place."
Mr Barron believes deep-sea mining is the "most ethical" and "best option" for acquiring metals needed for clean energy technologies.
"One of the challenges that society faces today, is that there is no zero impact activity and it's the same with us, we're not suggesting that there is no impact by going to pick up our rocks and turning them into battery metals," he said.
"What we are able to conclusively say is that our impacts are a tiny fraction compared with the known impacts of what's happening on land.
"There are no competing uses for this part of the sea floor, there are no people living there that you have to move out."
Shiva Gounden, head of Greenpeace's Pacific branch, disagrees and accuses supporters of deep-sea mining of "greenwashing".
"This narrative has been pushed by companies who are seeking to profit from this dangerous industry, saying if we need to transition into clean energy, we need minerals and it's a form of greenwash," he said.
"While we do need minerals for this green energy transition, mining and destroying the deep sea just isn't the way to go about it."
Mr Gounden instead believes the solution lies with minimising the amount of minerals extracted through mining, and gaining the metals through recycling instead.
"We can ensure that there are robust policies and societal changes that are aimed at driving energy and material reduction," he said.
'The ocean is everything'
Mr Gounden, who was born and raised in Fiji, said Pacific Islanders rely on the ocean for their livelihoods.
"The ocean is pretty much everything for them … they use the ocean as a very spiritual component of their lives, they're deeply interconnected with the ocean," he said.
The latest meeting of the ISA in Kingston has laid bare the deep divisions in the Pacific over deep-sea mining.
More than 30 countries, including Vanuatu, Palau, and Tuvalu in the Pacific, support a precautionary pause on deep-sea mining.
Others including Kiribati, Nauru, Tonga and the Cook Islands have all expressed interest in deep-sea mining exploration.
"It's very clear that there is a divergent narrative in the Pacific around deep-sea mining and a lot of it has to do with how these mining companies have used certain tactics or manipulation to buy the trust of certain countries," Mr Gounden said.
Mr Barron said his company is not mining any seabed affiliated with a Pacific nation but that some of the region's countries sponsor his company's licence applications to explore the Clarion-Clipperton Zone.
"We're purely focused on our licence areas in the CCZ in international waters."
Mr Gounden hopes for a "refreshing change" in the election of the next secretary-general of the ISA.
"What [the] ISA really needs is someone who follows the latest scientific evidence and is impartial and is independent and is a person who reflects values of integrity.
"I hope at this ISA a lot of states who are attending these sessions can stand on the right side of history and the right side of protecting our communities and protecting our ocean," he said.
The ABC approached Mr Lodge and the ISA for comment.
