By: Charlotte Ledwidge

The ocean is one of the last big mysteries of our planet that humans have yet to fully decipher. For decades the earth has been scoured and pulled apart for the missing pieces and answers to humanities crises and struggles. We have reworked the very surface we live on and broken the cyclical nature that allows life to flourish and continue. The ocean is even more fragile. It is complex and operates outside of parameters we are accustomed to as land dwellers. Life exists from the ocean surface to great depths, thousands of metres below sea level. Life there looks very different – no sunlight, extreme pressure and no human interference – until now. 

Since the 1970s, deep-sea mining has been an increasingly popular concept. The idea of extracting the Earth’s resources far away from terrestrial biodiversity has been branded by big mining corporations, such as The Metals Company (TMC), as the best alternative to current mining practices in the face of the ongoing climate crisis. Mining is under pressure with global decarbonisation and the energy transition reliant on elements acquired by extraction. However, the social and environmental dangers of  mining operations show that amplifying the current process is not the answer. Scientists are also determined however, that the exploitation of the deep-sea bed is not either. 

Much like the land we live on, the seabed is highly diverse in both topography and biodiversity. Abyssal planes, seamounts and hydrothermal vents are the areas of most interest for deep-sea mining endeavours. The Clarion-Clipperton Zone (CCZ), is an abyssal plain roughly equal in size to Europe found in the Eastern Pacific Ocean. Its seabed is smothered by dense gatherings of polymetallic nodules (spherical rocks) full of cobalt, nickel, copper, manganese and rare earth elements. It is these nodules that have caught the interest of mining corporations and state-owned companies. They exist just at the surface of the seabed and would be removed by underwater vehicles, pumped up through the water column in a tube that connects the vehicle to a vessel at the ocean surface where they would be processed and stored. TMC is one of the leading researchers in this technology to extract polymetallic nodules from the sea floor. The Canadian-based company has partnered with three island countries in the Pacific (Nauru, Tonga and Kiribati) to develop new projects close to the CCZ, with the NORI Allseas project being the most anticipated. 

The deep-sea floor is considered the common heritage of humankind, and when its exploitation was originally proposed, the interest of all nations on Earth was one of the main concerns expressed. Regulating and maintaining an equitable system of mining in international waters, that represents developing countries as well as the interests of private companies, was recognized as a complicated endeavour. In response, the International Seabed Authority (ISA) was established. The exploitation of the seabed outside of national jurisdiction falls into the hands of the ISA’s management. However, faith in the ISA and its ability to govern international waters is far from secure. A main source of this doubt comes from a conflict of interest within the ISA’s very purpose. Not only is it charged with managing the exploitation of the deep ocean’s resources, but it also must ensure the conservation of the deep-ocean environment and the preservation of biodiversity. The fate of an entire ecosystem, and the promise of a budding new economic endeavour are being weighed side-by-side on the same scale. 

Additionally, one of the main goals of the ISA is to ensure that developing countries are properly represented and provided with equal opportunities to access these resources without being pushed out by competing private sector companies. To address this, the ISA developed a system of exploration involving exploration contracts that any company or government can apply for. There are currently 31 exploration contracts under the ISA, most of which are for the CCZ. Any application for an exploration contract must contain two proposed areas of exploration, both of equal mineral merit. One will be used by that company or government for their own exploration, while the other will be reserved for development by The Enterprise or by developing nations. The Enterprise was a concept developed by the ISA under the United Nations Convention on the Law of the Sea, as an international mining company that would ensure the equal distribution of deep-sea minerals amongst all countries. The Enterprise still does not exist. 

The ISA is also under scrutiny for a lack of transparency. A 2023 report by the Deep Sea Conservation Coalition (DSCC) expressed concern over the running of the ISA, highlighting how any approved exploration contracts and any reports from exploration remain confidential and are withheld from ISA member countries and the public. An article by Harvard International Review mentions discussion between the ISA and TMC over mining locations, without the involvement of other ISA members, underpinning the distrust within the organisation. The ISA has yet to produce any finalised legal framework highlighting the regulations surrounding mineral exploitation and the nature of future exploitation contracts. With over 1m square kilometres of seabed currently under exploration, there is an overarching concern surrounding the environmental impacts of these destructive activities in such a delicate ecosystem, if exploitation under the ISA ever arises. 

Scientists are concerned that any form of exploitation on the deep-sea bed will harm valuable ecosystems beyond repair. The polymetallic nodules themselves are slow-forming structures and would take millions of years alone to recover post extraction. They are intrinsic to this biome we know so little about, despite years of investigation and scientific advancements. It is estimated that humans have only observed 0.01% of the deep ocean, a miniscule representation of an ecosystem that covers 66% of the Earth’s surface. 

Additionally, the distribution of observation dives is biased to exclusive economic zones off the coast of countries and along the continental shelves, meaning that even less is understood about the landscapes of the deep-sea bed. This lack of knowledge and certainty is one of the main arguments held by governments and scientists to try and slow down the drive for deep-sea mining. This concern has gained increased recognition in recent years and was pushed forward when Nauru imposed the two-year rule on the ISA in 2021, meaning that the ISA would have to produce a legal framework for deep-sea mining by 2023 or Nauru would be able to apply for an exploration contract. Furthermore, TMC USA underwent an exploitation application process through the National Oceanic and Atmospheric Administration in 2025. This poses additional concerns regarding differing regulations from different organisations and the imminent possibility of commercial exploitation by one of the largest privately owned companies in the business. Both TMC USA and Nauru Ocean Resources Inc. are subsidiaries of TMC, with the company’s position in the deep-sea mining world ever-growing. 

Scientific research predicts that deep-sea mining will drastically affect ocean biodiversity. For many marine organisms, sound is the primary means of communication, and fear over how deep-sea mining technology will impact them is paramount. The vessel on the ocean surface as well as the extraction vehicle on the sea floor will produce sound during operation which will be distributed throughout the water column. Additional concerns over increased light in the deep ocean are another source of unease. Life in the deep ocean has adapted to complete darkness, without the sun and photosynthesis. These life forms would now be subject to harsh brightness from machinery. The uncertainty surrounding these stark environmental changes and their being understudied is another reason why governments and conservationists are urging for a moratorium on deep-sea mining. Extensive biodiversity will inevitably be put on the line – biodiversity that regulates our ocean, sequesters carbon and operates in ways we barely understand. A BBC report cited research that predicts that 90% of all species in the CCZ alone are currently unknown to science. Questions have also arisen about the journey of migratory marine organisms and how they could become entangled in damage from deep-sea disruption. 

This concern is coupled with the sediment plumes that will be created by deep-sea mining operations. Two plumes will be created; one at the ocean floor as sediments are pulled up and the machine drags along the surface, and another from sediments and fluids being rereleased into the ocean on the way up to, or at the vessel. On TMC’s website, they urge that while these plumes are inevitable, they will settle within days and not travel further than four kilometres. However, the DSCC has predicted that these same plumes could extend beyond mining sites and cover thousands of square kilometres. The nature in which these sediments will settle is unknown and has the potential to be detrimental to niche, well-adapted ecosystems. There are also concerns over the impacts on filter feeders and organisms who rely on bioluminescence as well as around sediment getting trapped in the gills of marine organisms. 

The lack of trust in the ISA, its lack of decisiveness and general scientific uncertainty serve as proof to justify the establishment of a moratorium on deep sea mining. The ocean is vital to our planet; it is central to the functioning of ecosystems on land and an abundance of mystery below the water. It is a colourful, thriving recluse, even in the dark depths. It already faces pressure from climate change, pollution, over-fishing and ocean acidification. The cumulative effects of these alone are hurting the ocean. Deep-sea mining has the potential to cause it more stress. Mining is bad for people and for the planet, whether on land or in the ocean. Governments should instead invest time and money in the recycling of existing minerals and in innovation through enhancing or modifying existing technology to rely less on the Earth’s raw resources. The mystery of the ocean adds to its beauty, and it already has a purpose, as a home and as a critical habitat.