Law Of Sea: A View On Divison Of Sea As Per UNCLOS 1982

This article is written by Saloni Gautam from JIMS School of Law

Table of Contents


The sea has been one of the reasons and helpers in the modern development of humankind and hence the importance of the sea cannot be overlooked by any country. Law on the sea was evolved during the time of Grotius and they were observed by the States as customary rules of International Law. Keeping the importance of the sea in mind, some states started extending their area of control over the sea, like Russia claimed the territorial zone up to 12 miles and few other states claimed till four miles, which were inconsistent with the customary rules and hence the need of codification of the law of the sea was felt. Various conferences were held for the purpose of codification but none of them succeeded till the United Nations Conference on Law of Sea (UNCLOS). In this conference, the convention was adopted. The convention is known as the United Nations Convention on Law of Sea, 1982 which is the governing convention in matters dealing with Sea and the disputes arising in the sea.

Division of sea as per the convention

The sea was traditionally divided into three parts as given below:

Territorial Waters

The sovereignty of the state is confined not only to the waters and land lying within its boundaries. It also extends to a part of the sea which is adjacent to the Coastal state. “Territorial waters” or “Territorial sea” can be defined as that part of the sea which is adjacent to the coast and over which International law permits the coastal states to exercise sovereignty over the territorial waters but the only restriction is to the right of innocent passage. The possession of this territory is neither optional, nor dependent upon the will of the state, but compulsory1.  There are two important factors to be considered here;

  • Territorial Breadth

Although the states have agreed on the exercise of sovereignty of the state over territorial waters, the controversy may arise on the extent or breadth. The extent of the territorial jurisdiction was based on the ‘Cannon Shot’ rule. The general rule for deciding territorial breadth can be put in the words of De Dominio Maris, “Wherefore on the whole it seems a better rule that the control of the land over the sea extends as far as cannon will carry, for that is as far as we seem to have both command and possession. I should have to say in general terms that the control from the land ends where the power of man’s weapons ends.”

As per the Geneva Conference, there were various claims with regard to the breadth of the territorial sea. The Convention of 1982 finally dealt with the question of breadth of the territorial sea and under Article 3, it said that territorial sea can extend up to a maximum of 12 nautical miles and not more than that. It also deals with the conditions where two coasts of two different states are situated “opposite or adjacent, neither of the two states is entitled, failing agreement between them to the contrary, to extend its territorial sea beyond the median line every point of which is equidistant from the nearest points on the baselines from which the breadth of the territorial seas of each of the two states” is measured as stated in Article 15 of the convention of 1982.

  • Right to innocent passage

Right to innocent passage is the right conferred to other states that the vessels of all states can use the territorial sea as a passage when they don’t have any mala fide intention. The term passage may be defined as passing through the territorial sea from high sea to high seas, and proceeding to or from a port. The entry of the foreign ships, upon the territorial water for any other purposes of travelling the territorial sea, and if it enters for any other purposes, even though its actions amount only to passing in the sense defined, it is not an innocent passage. This has been defined as similar as given above in paragraph 1 of Article 18.

Contiguous Zone

Contiguous zone is that part of the sea which is beyond and adjacent to the territorial waters of the coastal state where the coastal state does not exercise sovereignty over the sea beyond territorial waters, however, they may take appropriate action to protect its revenue and other matters. The police revenue jurisdiction and the respective coastal states spreads to the contiguous zone.  

The limit of the contiguous zone was provided in the Geneva Convention of 1958. It was to extend 12 miles starting from baselines of which the breadth of the territorial sea is measured as provided in the Geneva Convention of 1958. The limit of the contiguous zone has been extended by the convention of 1982 which provided under article 33 that the contiguous zone may not extend 24 nautical miles starting from the baseline of which the territorial sea’s breadth is measured.

High Seas

The high sea or open sea can be said to be the sea outside the territorial waters, contiguous zone etc. In Article 1 of the Geneva Convention, the High Seas are defined. “All parts of the sea that were not included in the territorial sea or in the internal waters of a state.” This definition of the Geneva Convention has proven to be extremely absolute and inadequate in view of recent developments. It merely mirrors the customary international law. Although, the definition in Article 86 of 1982 Convention is as follows; “…all parts of the sea that are not included in the Exclusive Economic Zones, in the territorial sea or internal waters of a State, or in the archipelagic waters of an archipelagic State…”

Article 87 of the 1982 Convention states that “High seas are open to all states and that the freedom of the high seas is exercised under the conditions laid down in the convention and by other rules of international law.”

Exclusive Economic Zone

The Exclusive Economic Zone is best described as a sea belt which is adjacent to the coast, extending up to 200 miles from the territorial sea’s baseline. Confined in this area, the coastal state has granted “Sovereign rights” with the purpose of exploring or exploiting living/non-living natural resources of the sea. Article 57 of the UNCLOS, 1982 deals with the breadth of the exclusive economic zone and states that the exclusive economic zone shall not extend beyond 200 nautical miles initiating through the baseline from which the territorial sea’s breadth is measured. 

Continental Shelf

The Continental shelf as per the definition of UNCLOS, 1982 in Article 76 is to comprise of the seabed and subsoil of the submarine areas of a coastal State which exceed beyond the territorial sea and throughout the natural prolongation of land territory and to the exterior edge of continental margin. (The continental margin comprises the geological shelf, slope and rise.) or upto 200 nautical miles starting from the baselines of territorial seas, where the exterior edge of continental borders do not extend. As the continental shelf is a geographical factor which cannot be controlled and it may extend beyond the limit of 200 Nautical Miles. In order to avoid conflicts in such matters, the outer limits of the Continental shelf as prescribed by the UNCLOS, 1982 are 350 Nautical miles and no state can claim any continental shelf exceeding this limit.


After knowing the division of sea as done for the convenience of the humans, to avoid conflict and to preserve the sea and its resources safe from being exploited, we can say that the Law of sea which was one of the subjects governing customary law in international regime has been codified and even after having so many disputes in the breadths of the divisions it is now resolved after framing of the United Nations Convention on Law of Sea, 1982, which defined the breadths as well as the rights of coastal and other states as well. It has further settled a body to take care of the disputes arising on the international level involving any issue relating to laws of the sea. 

The convention has contributed much in the codification and simplification of the law of sea but the leading cases in respect of the law of sea cannot be ignored. The North Sea Continental Shelf Case, The Lotus Case2, Anglo-Norwegian Fisheries Case3, Qatar v. Bahrain4, Tunisia v. Libya Continental Shelf Case5, Saint Vincent and the Grenadines v. Guinea6 etc. can be named as few but there are various concepts as explained through the help of cases and has lead to better and clear definition of various things and the contribution of these cases cannot be ignored.


  1. Anglo-Norwegian Fisheries Case, [1951] ICJ Rep 116
  2. (1927) PCIJ Series A no 10
  3. Supra Note 1
  4. [1994] ICJ Rep 112
  5. [1982] ICJ Rep 18
  6. ITLOS Case No 1

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