Life itself arose from the oceans. The ocean is vast and covers 140 million square miles, some 72 per cent of the Earth's surface. The ocean has always been an important source of food for the life it helped generate, and from earliest recorded history it has also served trade and commerce, adventure and discovery. It has separated and brought people together.

Even now, when the continents have been mapped and their interiors made accessible by road, river and air, most of the world's people live no more than 200 miles from the sea and relate closely to it.

A historical perspective on the law of the sea

The oceans had long been subject to the freedom of-the-seas doctrine - a principle put forth in the 17th century, essentially limiting national rights and jurisdiction over the ocean to a narrow sea belt surrounding a nation's coastline. The rest of the seas were declared free for all and belonged to none. While this situation lasted into the twentieth century, by mid-century there was an impetus to extend national claims over offshore resources.

A tangle of maritime claims, spreading pollution, competing demands for fish stocks in coastal waters and adjacent areas, growing tension between coastal nations' rights to these resources and those of distant-water fishers, prospects of a rich harvest of resources on the sea floor, the increased presence of maritime powers and the pressures of long-distance navigation and a seemingly outdated, freedom-of-the-seas doctrine - all these were threatening to transform the oceans into another arena for conflict and instability.

In the mid-twentieth century, many States recognized the need to set down rules for all ocean areas and all uses of the ocean and its resources, through a comprehensive treaty. After two conferences held in 1958 and 1960, respectively, the Third United Nations Conference on the Law of the Sea was convened in 1973. Following nine years of negotiations, the United Nations Convention on the Law of the Sea was adopted in 1982. Adopted as a “package deal”, the Convention incorporates agreed compromises and balances competing interests, producing an intricately balanced text to provide a basis for universal adoption.

United Nations Convention on the Law of the Sea (UNCLOS)

As recalled annually by the General Assembly, the United Nations Convention on the Law of the Sea sets out the legal framework within which all activities in the oceans and seas must be carried out. It is of strategic importance as the basis for national, regional and global action and cooperation in the marine sector, and its integrity needs to be maintained.

The Convention was opened for signature on 10 December 1982 in Montego Bay, Jamaica, and entered into force on 16 November 1994. At the time of its adoption, the Convention embodied in one instrument traditional rules for the uses of the ocean and at the same time introduced new concepts and addressed new concerns. The Convention also provided the framework for further development of specific areas of the law of the sea. For these reasons, it is often referred to as the “constitution for the oceans”.

The Convention comprises 320 articles and nine annexes, governing all aspects of ocean space, including the rights and obligations of coastal and other States in different maritime zones, the delimitation of maritime boundaries, protection and preservation of the marine environment, marine scientific research, the development and transfer of technology and the settlement of disputes, among others.

The Convention also provided for the establishment of the International Seabed Authority (ISA), the Commission on the Limits of the Continental Shelf (CLCS) and the International Tribunal for the Law of the Sea (ITLOS). ISA organizes and controls activities in the seabed beyond national jurisdiction with a view to administering its resources. The CLCS facilitates the establishment of the outer limits of the continental shelf beyond 200 nautical miles by considering data submitted by coastal States and making recommendations. ITLOS has competence to settle ocean-related disputes arising from the application or interpretation of the Convention.

Protection of Biodiversity and Climate Change
A harbor seal at the Elkhorn Slough Ecological Reserve, an estuary located along Monterey Bay in California, United States. UN Photo/Mark Garten

Protection of marine environment and biodiversity

UNCLOS has an entire Part dedicated to the protection and preservation of the marine environment (Part XII), but environmental provisions are also found in other Parts of the Convention, including article 1, which contains a definition of “pollution of the marine environment” as “the introduction by man, directly or indirectly, of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of sea water and reduction of amenities”. The ITLOS has also concluded that anthropogenic greenhouse gas emissions into the atmosphere fall within this definition.

Part XII opens with a series of general obligations, including the obligation of States to protect and preserve the marine environment. This fundamental obligation embodies a radical change from the piecemeal approach adopted in previous instruments. It applies with regard to all activities and in all maritime zones. States also have the obligation to take all measures necessary to prevent, reduce and control pollution of the marine environment from any source. The Convention also addresses biodiversity as it requires that necessary measures be taken to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life.

Under UNCLOS, States are required to cooperate on a global and, as appropriate, on a regional basis, directly or through competent international organizations, in formulating and elaborating international rules, standards and recommended practices and procedures consistent with UNCLOS, for the protection and preservation of the marine environment, taking into account regional characteristics.

UNCLOS is supplemented by three implementing agreements, namely the 1994 Part XI Agreement, the 1995 United Nations Fish Stocks Agreement (UNFSA) and the BBNJ Agreement (see below), which all include provisions on the protection and preservation of the marine environment.

In addition, the provisions of UNCLOS on the protection and preservation of the marine environment are supplemented and further elaborated upon by a vast number of sectoral instruments, either binding or non-binding, adopted both at the global and regional level, that address specific issues and priorities.

At the global level, the International Maritime Organization (IMO) is the specialized agency of the United Nations that is responsible for developing and adopting global regulations to improve the safety and security of international shipping and to prevent pollution from ships (also see below). Some of the key conventions adopted under the auspices of IMO include the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78), the International Convention for the Safety of Life at Sea (SOLAS) and the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, also known as the London Convention, as well as it 1996 Protocol.

The international legal framework for the protection and preservation of the marine environment also includes a number of international instruments specifically addressing the protection of marine biodiversity and ecosystems, such as the United Nations Convention on Biological Diversity, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, and the Convention on the Conservation of Migratory Species of Wild Animals.

The UN Environment Programme (UNEP) also plays an important role in promoting the protection, conservation, restoration and sustainable management of marine and coastal areas. The UNEP Regional Seas Programme is UNEP's most important regional mechanism for conservation of the marine and coastal environment since its establishment in 1974. It consists of three types of Regional Seas Conventions and Action Plans (RSCAPs) across 18 different regions (UNEP administrated, non-UNEP administrated and independent). In addition, UNEP serves as the secretariat of the Global Programme of Action (GPA) for the Protection of the Marine Environment from Land-based Activities, which was adopted in 1995 with a view to addressing the accelerating degradation of the world’s oceans and coastal areas.

Following a resolution adopted by the United Nations Environment Assembly in 2022, negotiations are currently underway to develop a legally binding instrument on plastic pollution, including in the marine environment.

Other relevant global instruments include the outcomes of the United Nations Conferences related to sustainable development. The 2030 Agenda for Sustainable development is the latest example. It includes important environmental considerations in its 17 Goals and 169 targets, including in particular Sustainable Development Goal 14: "Conserve and Sustainably use the oceans, seas and marine resources for sustainable development".

Furthermore, the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) is identified in UNCLOS (Annex VIII) as the competent organization in the field of marine scientific research. Its mission includes to promote international cooperation and to coordinate programmes with a view to enhancing knowledge about the nature and resources of the ocean and coastal areas and applying that knowledge for the improvement of management, sustainable development, the protection of the marine environment, and the decision-making processes of its Member States.

In 2017, the United Nations General Assembly proclaimed the UN Decade of Ocean Science for Sustainable Development (2021-2030), also known as the Ocean Decade. This decade aims to promote ocean science and knowledge generation to improve the state of the ocean system and facilitate sustainable development of this vast marine ecosystem.

The vision of the Ocean Decade is to achieve "the science we need for the ocean we want". The initiative provides a framework for scientists and stakeholders from various sectors to collaborate and develop the scientific knowledge and partnerships required to expedite and leverage progress in ocean science. These efforts can lead to a better understanding of the ocean system and deliver science-based solutions to achieve the 2030 Agenda.

The UN General Assembly tasked IOC/UNESCO with coordinating the preparations and implementation of the Decade.

Finally, given the vital role that the ocean plays in climate regulation and mitigation, enhanced international cooperation and coordination is key to addressing the effects of climate change on the ocean. Several international instruments contain provisions to that effect. These include the United Nations Framework Convention on Climate Change and the 2015 Paris Agreement.

A historic new treaty on marine biodiversity

Areas beyond national jurisdiction, which include the high seas and the international seabed area (“the Area”), cover over two-thirds of the ocean. They are home to rich biodiversity and provide humanity with many goods and services. Yet, they are vastly underexplored and have traditionally suffered from little attention and funding in terms of research.

These areas are also increasingly affected by anthropogenic pressures, such as destructive fishing practices, pollution and climate change, which, cumulatively, put the health and resilience of the ocean at risk.

The United Nations General Assembly, in 2004, launched a process which took place in various formats over nearly two decades and culminated in the adoption by consensus, on 19 June 2023, of the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement).

Under the overall objective of ensuring the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction, for the present and in the long-term, through effective implementation of the relevant provisions of the Convention and further international cooperation and coordination, the BBNJ Agreement addresses a package of four issues and several cross-cutting issues.

The four issues covered by the BBNJ Agreement are: marine genetic resources, including the fair and equitable sharing of benefits; measures such as area-based management tools, including marine protected areas; environmental impact assessments; and capacity-building and the transfer of marine technology.

The BBNJ Agreement is the third implementing agreement to UNCLOS and the first comprehensive cross-sectoral ocean treaty in decades. By establishing specific mechanisms for cross-sectoral cooperation and coordination, the Agreement has the potential to lead to more integrated, holistic approaches to the management of ocean activities.

The BBNJ Agreement marks a vital milestone in multilateral efforts to reverse the destructive trends facing the ocean, restore ocean health and resilience, and establish a greater level playing field for States to participate in and benefit from ocean activities. Its timely and effective implementation can make vital contributions to addressing the triple planetary crisis of climate change, biodiversity loss and pollution, and to achieving ocean-related goals and targets, including those of the 2030 Agenda for Sustainable Development, particularly Goal 14, and the Kunming-Montreal Global Biodiversity Framework.

Sustainable fisheries

Marine living resources, including fish, continue to provide an important source of food and nutrition, contribute to livelihoods and economic development, have immeasurable socio-economic and cultural value and are vital for the health and resilience of marine ecosystems. However, the sustainability of global fish stocks is threatened by such factors as overfishing, including as a result of illegal, unreported and unregulated fishing and overcapacity, as well as ecosystem degradation as a result of anthropogenic stressors which undermine the health, resilience and productivity of marine ecosystems. Such stressors include ocean warming, ocean acidification, pollution and destructive fishing practices.

The United Nations Convention on the Law of the Sea provides an overarching international legal framework for the conservation and sustainable use of marine living resources. It is complemented by the 1995 United Nations Fish Stocks Agreement, which provides a more detailed legal regime for straddling fish stocks and highly migratory fish stocks – two important categories of commercially exploited high seas fish stocks, as well as various binding and non-binding international instruments on fisheries.

The Food and Agriculture Organization of the United Nations, as the United Nations Specialized Agency with competence over fishing, has developed a range of these binding and non-binding instruments, including the Agreement on Port State Measures to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing, the Agreement to Promote Compliance with International Conservation and Management Measures by Fishing Vessels on the High Seas and the Code of Conduct for Responsible Fisheries.

The International Maritime Organization (IMO) is the key United Nations institution for the development of international maritime law. Its main task is to create a fair and effective, generally accepted and implemented legal framework for the shipping industry.

Marine shipping and pollution

To ensure that international shipping is cleaner and greener, IMO has adopted comprehensive regulations to address pollution from ships, including binding energy-efficiency measures to reduce (GHG) greenhouse gas emissions. In 2024, IMO adopted a revised strategy with a collective ambition to achieve net-zero GHG emissions for international shipping by 2050 and a commitment to foster the adoption of alternative zero and near-zero GHG-emitting fuels by 2030.

Polar Code

The safety of ships operating in the harsh, remote and vulnerable polar areas and the protection of the pristine environments around the two poles have been a matter of concern for IMO over many years. Many relevant requirements, provisions and recommendations have been developed by IMO, in light of the unique risks that ships are exposed to in the Arctic and Antarctic environments.

In this connection, in January 2017, IMO's International Code for Ships Operating in Polar Waters (Polar Code) entered into force. The Polar Code covers the full range of design, construction, equipment, operational, training, search and rescue and environmental protection matters relevant to ships operating in the inhospitable waters surrounding the two poles. The Polar Code was an important regulatory development in international shipping, alongside a range of regulatory developments relating to maritime and supply chain security and environmental issues.

Piracy

MONUSCO peacekeepers land at beach to guard against piracy
MONUSCO peacekeepers land at beach to guard against piracy in the Democratic Republic of the Congo. UN Photo/Sylvain Liechti

In recent years there has been a surge in piracy, as well as armed robbery against ships, off the coast of Somalia and in the Gulf of Guinea. Pirate attacks are a danger to the welfare of seafarers and the security of navigation and commerce. These criminal acts may result in the loss of life, physical harm or hostage-taking of seafarers, significant disruptions to commerce and navigation, financial losses to shipowners, increased insurance premiums and security costs, increased costs to consumers and producers, and damage to the marine environment.

Pirate attacks can have widespread ramifications, including preventing humanitarian assistance and increasing the costs of future shipments to the affected areas. The IMO and UN have adopted additional resolutions to complement the rules in the United Nations Convention on the Law of the Sea Convention for dealing with piracy.

The United Nations Office on Drugs and Crime (UNODC), through its Global Maritime Crime Programme (GMCP) combats transnational organized crime in Africa focusing on countering piracy of the Horn of Africa and Gulf of Guinea. The programme has delivered support to states in the region to assist them in by carrying out trials and imprisonment of piracy suspects as well as developing maritime law enforcement capabilities through the facilitation of training programmes. From the piracy prosecution model, prisoner transfers and training of members in the judicial system of the Atlantic and Indian Ocean, to full-time mentoring to coast guards and police units in Somalia, Kenya and Ghana, the UNODC GMCP has accomplished many successes in a challenging environment. This has been achieved through a variety of programmes aimed at promoting maritime safety and security and bolstering the countries' rule of law and justice systems.

The International Maritime Organization also provides assistance, to Member States seeking to develop their own national or regional measures to address the threat of piracy, armed robbery against ships and other illicit maritime activities, if and when requested. This was the case of the Code of Conduct concerning the Repression of Piracy and Armed Robbery against Ships in the Western Indian Ocean and the Gulf of Aden (Djibouti Code of Conduct), agreed between countries in and around the western Indian Ocean, and the case of the Code of Conduct concerning the repression of piracy, armed robbery against ships, and illicit maritime activity in west and central Africa, in the Gulf of Guinea region of West Africa. Through the IMO Djibouti Code Trust Fund, several projects and activities have been designed, coordinated and implemented by the IMO Secretariat's Project Implementation Unit, to improve regional capacity to counter piracy by promoting and enhancing regional cooperation and coordination, based on four pillars: Training, Capacity Building, Legal and Information Sharing.

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