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


The United Nations Convention on the Law of the Sea (UNCLOS), often referred to as the ā€œConstitution for the Oceans,ā€ is an international treaty designed to establish a legal framework to regulate all ocean space, its uses, and resources.

UNCLOS essentially provides a framework that defines countries' own national rights to the seas and oceans along their coastline, whilst also clearly defining international waters - that is, the areas beyond national boundaries that are free to all nations and belong to no-one. This covers a broad range of topics including territorial waters, exclusive economic zones, navigation, marine scientific research, and the conservation of marine life.


Historically the principle of "freedom of the seas" stressed the freedom of all to navigate the oceans in international waters. That is, that effectively no-one owns international waters, and so anyone can use those areas.

Conversely, nations claimed the rights to areas of seas extending beyond their coasts, usually to a distance of around 3 nautical miles according to the "cannon shot" rule developed by Cornelius van Bynkershoek. In effect, nations could control the waters that they could shoot from land, but waters beyond that distance were international and owned by no-one.

The early 20th century saw rapid increases trade, fishing activity and marine mineral exploration (especially for oil and gas). This resulted in nations staking claims to areas further from their land (in some cases up to 200 nautical miles from their coast), often inconsistently.

A sailing clipper in high seas

UNCLOS I (concluded in 1958), UNCLOS II (discussed in 1960) and UNCLOS III (signed 1982, and effective as of 16th November 1994) sought to confirm and standardise claims to the oceans, their uses and their resources.

Legal Zoning of Waters

UNCLOS defines various areas according to their distance from a baseline (normally the sea's low-water line), as follows:

Maritime zoning of waters per UNCLOS Maritime zoning of waters per UNCLOS
  1. Internal Waters - these are all waters on the landward side of the baseline, and the state is free to set laws and regulate their use.
  2. Territorial Sea - up to 12 nautical miles from the baseline. The state is free to set laws, regulate the use and any resources.
  3. Exclusive Economic Zone - up to 200 nautical miles from the baseline. The state has sole exploitation rights of mineral resources (historically oil and gas, but increasingly subsea minerals)
  4. Extended Continental Shelf - in cases where the continental shelf continues contiguously out into the ocean, a state may extend their claim up to 350 nautical miles
  5. "The Area" - also known as the "High Seas" or "International Waters", this area of the ocean is beyond national jurisdiction, and freedom of the seas applies. Minerals in The Area are controlled by the International Seabed Authority


UNCLOS has been signed by 168 countries and the EU:

World map showing signatories of UNCLOSKey for world map showing signatories of UNCLOS Signatories of UNCLOS

Note that UNCLOS has not been signed by the United States. Indeed, whilst the US was involved in shaping the Convention and its revisions, it has various objections.

The Essence of UNCLOS

Territorial Sea and Contiguous Zone

Every coastal nation has sovereignty over its territorial sea, which extends up to 12 nautical miles from its coastline.

Exclusive Economic Zone (EEZ)

Coastal states have special rights to explore and exploit marine resources, including energy production from water and wind, in their EEZ, which extends 200 nautical miles from the coast.

Continental Shelf

This is the extended margin of each continent and associated coastal plain. Coastal states have rights over the natural resources of their continental shelf.

Navigation and Overflight Rights

UNCLOS guarantees the right of ships and aircraft of all countries to navigate freely on, over, and through international straits.

Importance in Deep-Sea Mining

The world's oceans are filled with abundant volumes of subsea mineral resources. Some of these resources lie within EEZs, but the vast majority are located in The Area, and so are regulated by UNCLOS and the ISA:

Map of the world indicating the location of subsea minerals Map of the world indicating the location of subsea minerals

In particular, polymetallic nodules typically occur on the deep abyssal plains of the world's oceans, far from land and far from the continental shelf. The most highly studied area of polymetallic nodules is in the Clarion-Clipperton Zone (CCZ), which lies between Hawaii and Mexico in the middle of the North Pacific.

The CCZ is many hundreds of nautical miles from land, and so falls under the jurisdiction of the ISA. Indeed, the ISA has issued many subsea mineral exploration licenses for this area:

Map of the Clarion-Clipperton Zone, showing subsea mineral exploration licenses issued Map of the Clarion-Clipperton Zone, showing subsea mineral exploration licenses issued

The International Seabed Authority (ISA)

The International Seabed Authority (ISA) was established by UNCLOS in 1994. It serves as an autonomous organization with a key mandate to oversee deep seabed mining beyond the limits of national jurisdiction, with the objective of ensuring that these activities are carried out for the benefit of all humankind.

Mandate and Jurisdiction

ISA ensures that the marine environment is protected from harmful effects which may arise during mining activities in the international seabed area, commonly referred to as "the Area".


All members of the United Nations who ratify UNCLOS are eligible to be part of ISA.


The ISA regulates mineral-related activities in the international seabed area. This involves granting licenses, framing rules and regulations, and ensuring that there is no harm to the marine environment.


ISA has a Council and an Assembly, which take decisions on administrative, financial, and substantive issues. There's also a Legal and Technical Commission which provides specialized advice.

Resource Sharing

The benefits from mineral resources in the Area are shared on a non-discriminatory basis among ISA member states, with emphasis on distributing a portion to developing countries.


UNCLOS and its creation, the International Seabed Authority, represent landmark attempts to bring governance, fairness, and environmental stewardship to the world's oceans. While challenges remain, the framework they provide is essential for the sustainable use and conservation of marine resources.

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Phillip Gales is a serial entrepreneur who has built tech companies in various heavy industries including Oil & Gas, Construction, Real Estate and Supply Chain Logistics. Originally from the UK, he now lives in Toronto, Canada, with his wife and young family.

Phillip holds an MBA from Harvard Business School, and an MEng in Electrical Engineering from the University of Cambridge, specialising in Machine Intelligence.