Into the Depths: International Law and Deep Seabed Mining

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The oceans are much deeper than we think. The high seas – defined in international law as the waters beyond all national territorial waters and exclusive economic zones (EEZs) – extend to depths ranging from an average of over 4,000 metres to a maximum of over 10,000 metres. Making up almost half of Earth’s surface, the high seas contain nearly 95% of the planet’s habitat. Moreover, oceans are home to an estimated 700,000 to 1 million species. Scientists continue to discover new species and ecosystems, many of them on the deep seabed floor.

Certain areas of the deep seabed are also home to significant ore deposits. These can potentially be mined and used to meet increasing demand for valuable metals used in modern and clean technologies.

This HillNote outlines the opportunities and risks of deep seabed mining. It traces the current state of negotiations behind the regulations that will govern deep-sea life and activity for the foreseeable future. It also describes Canada’s role in the International Seabed Authority.

Deep Seabed Mining

Deep seabed mining is much like terrestrial mining. Minerals or metals of interest are found and extracted when economically viable. In addition to searching for cobalt-rich ferromanganese crusts and polymetallic sulphides, mining companies often explore the deep seabed to find polymetallic nodules. Polymetallic nodules are composed of different metals in varying ratios. The largest part is often manganese, with smaller – and more valuable – nickel, copper or cobalt deposits.

Over the last several years, technological advancements and exploration have made the mining of deep-sea ore deposits more viable. Several types of extraction technologies exist. The best known are hydraulic mining systems, “which pick up the nodules with a towed or self-propelled harvester [or collector vehicle] and then lift them to the surface with simple hydraulic or air-assisted lift systems.”

Figure 1 – Deep Seabed Mining Operations

The image depicts an ocean ecosystem alongside a hydraulic mining system. Various marine species are depicted in the water column’s various vertical zones, which are: the sunlight zone (surface to 200 metres in depth), the twilight zone (200 metres to 1,000 metres), the midnight zone (1,000 metres to 4,000 metres) and the abyss (4,000 metres to 6,000 metres). Collector vehicles collecting polymetallic nodules are shown on the seabed along with a collector pipe that runs from the vehicles to a vessel on the surface. Collector and dewatering plumes along the water column are also shown.

Source: Figure prepared by the Library of Parliament using data obtained from Elizabeth Claire Alberts, “Sediment plumes from deep-sea mining could pollute vast swaths of the ocean, scientists say,” Mongabay, 20 July 2020; and International Seabed Authority, Polymetallic Nodules.

The Law of the Sea

The high seas – and the seabed beneath them – are governed by the United Nations Convention on the Law of the Sea (UNCLOS). Signed by Canada in December 1982 and ratified in November 2003, most of UNCLOS is now generally considered to be customary international law. This means that the convention applies to all states regardless of whether they are parties.

UNCLOS “governs relations among countries on ocean-related issues,” such as the establishment of national territorial waters and EEZs, navigation rights and ocean protection. It also creates a regulatory regime relating to deep seabed minerals. Under UNCLOS, the International Seabed Authority (ISA) – of which Canada is a member – regulates deep seabed prospecting, exploration and exploitation through its Mining Code. The code applies to “the seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction” (“the Area”).

To date, the ISA has finalized only the exploration portion of the Mining Code, under which it has approved 30 contracts for exploration involving 22 countries and covering over 1.3 million km2 of the seabed.

Exploration may soon turn to exploitation, however. In June 2021, the small island state of Nauru – in partnership with a Canadian mining company, DeepGreen Metals – sought permission from the ISA to exploit minerals from four areas, shown in Figure 2. This request triggered a UNCLOS clause that requires the ISA to finalize, within two years, the exploitation regulations, or “consider and provisionally approve” the request.

Figure 2 – Map of the Proposed Mining Areas

This map shows the location of the four proposed mining areas in the Pacific Ocean. From west to east, these are: Area A with a surface of 8,924 km2, Area B with a surface of 3,519 km2, Area C with a surface of 37,227 km2 and Area D with a surface of 25,160 km2.

Source: Map prepared by the Library of Parliament, Ottawa, 2022, using data from the International Society of Automation, ISA contract for Exploration – Public Information Template; Natural Earth, 1:10m and 1:50m Cultural Vectors and 1:50m Physical Vectors, version 4.1.0; and General Bathymetric Chart of the Oceans, GEBCO_2021 Grid, accessed 5 May 2022. The World Imagery base map is the intellectual property of Esri and is used under licence, © 2022 Esri and its licensors. The following software was used: Esri, ArcGIS Pro, version 2.9.1.


The chief benefits of allowing deep seabed mining are economic and environmental. Terrestrial deposits of nickel, copper and cobalt are depleting, and demand for these metals is rising. Deep seabed deposits are a new, untapped source of these metals, many of which are needed for clean technologies, such as lithium-ion batteries for electric vehicles.

More broadly, deep seabed mining opens new opportunities for economic development. This is especially true for Canada, which is home to “almost half the world’s publicly listed mining and mineral exploration companies.”

As well, deep seabed mining potentially means less mining on Earth’s surface, an often highly expensive process. Terrestrial mining is also costly for the environment and can negatively affect human rights. By relocating the mining of rare metals, deep seabed mining potentially decreases pressure on vulnerable communities and terrestrial environments.


At the same time, mining activity in the Area risks damaging deep-sea ecosystems, the overall ocean system and the economies that depend on ocean life.

In the case of hydraulic mining, the ISA notes that collector vehicles can crush or bury organisms and habitat structures located on the sea floor. As hard surfaces on the soft seabed floor, polymetallic nodules are important structures for seabed creatures, such as sponges, and the ecosystems that depend on them. Scientists warn that removing these deposits “would trigger a cascade of negative effects on the ecosystem.” It is also unclear how long it would take a mined seabed to recover.

In addition, disturbance of sea floor sediment can impact water turbidity, clarity and chemical composition. Collector vehicles kick up plumes of sediment. Dewatering pipes discharge wastewater in similar sediment clouds. Both types of plumes can make waters toxic to species living at different levels of the water column. For instance, they can clog the delicate water filters of some creatures and obscure the light that others, living in the deep sea, need to hunt and mate. Noise pollution from equipment can also negatively affect organisms, such as whales.

The far-reaching effects of deep seabed mining on ecosystems and ocean systems remain unknown. Any mining of deposits near North America, for instance, may affect biodiversity, water quality and the health of Canadian fish stocks. Major ocean currents could also spread the effects into Canada’s Arctic waters.

While deep seabed mining may help power the clean technology revolution, how deep-sea ecosystems currently affect carbon sequestration is yet unknown. Changing the carbon cycle may, in fact, contribute to climate change. If so, this could outweigh the positive environmental effects of displacing more carbon-intensive technology.

As the International Union for Conservation of Nature (IUCN) puts it, the “deep sea remains understudied and poorly understood, [and] there are many gaps in our understanding of its biodiversity and ecosystems.” Premature or overly permissive regulations could irreversibly harm an ocean system that scientists are just beginning to understand. Critics call for a precautionary approach.

Current Situation

The IUCN – of which several Canadian federal departments are members – adopted Resolution 122 in September 2021. It requests a moratorium on deep seabed mining until certain conditions are met, including “rigorous and transparent impact assessments.” In Canada, a petition calling for a moratorium was presented to the House of Commons on 5 April 2022.

At the present time, the ISA deep seabed mining regulations exist only in draft form, dating from 2019. Their final form must be approved by the ISA Council, on which Canada presently holds a seat. Discussion of the regulations appeared on the Council’s meeting agenda for spring 2022.

Once approved by the Council, the new section of the Mining Code must be approved by consensus by the ISA Assembly, which is made up of 167 member states and the European Union. Given the two-year rule triggered in June 2021, the ISA – including Canada – will soon have to make decisions on regulations that will govern the deep ocean for years to come.


By Daniele Lafrance and Martin McCallum, Library of Parliament

Categories: Agriculture, environment, fisheries and natural resources, Business, industry and trade

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