Continental Shelf: Definition, Method of Determination, and Its Presence in Indonesia

Continental Shelf – Sinaumed’s must have known that on this planet Earth, 70% of its surface is water area. But even so, not all countries in the world have territorial waters in the form of seas. Meanwhile, countries that have territorial waters or seas can be categorized as coastal countries, namely a country whose land area is bordered by the sea. This coastal country can also be called an archipelagic country. Well, in this case, Indonesia is clearly included in the category of a coastal country, aka an archipelagic country, right ?

Since Indonesia has land and water areas that are both connected to many countries, of course there is an international law of the sea. The existence of the international law of the sea is not merely an ordinary law, you know, but is also expected to be able to regulate the country concerned with other countries regarding the maritime boundaries they have. Just a little trivia , it turns out that it took almost 30 years to discuss provisions relating to the international law of the sea! Well, in international law of the sea there is the term Continental Shelf. Then, what is the definition of the Continental Shelf? What is the history of the formation of rules regarding the Continental Shelf? Let’s look at the following reviews, so that Sinaumed’sunderstand these things!

What is the Continental Shelf?

Basically, the Continental Shelf is included in UNCLOS (United Nations Convention on The Law of The Sea) 1982, which has also been adopted into Law No. 17 of 1985 concerning Ratification of UNCLOS. So, in UNCLOS 1982, it states that the total sea area owned by the Indonesian state is around 5.9 million km², with an estimated area of ​​3.2 million km² of territorial waters and 2.7 million km² of waters in the Exclusive Economic Zone. This area does not include the area of ​​the Continental Shelf . Therefore, UNCLOS 1982 also stated that our country, Indonesia, is the largest archipelagic country in the world.

The geographical definition of the Continental Shelf is a gentle slope covered by shallow water that flows from the shoreline of a collection of land masses before dropping sharply into the ocean waters. There is another definition of the Continental Shelf according to geology, namely (that part of the ocean floor (oceans) that is connected to the coast of a continent and which is covered by shallow waters, which is less than 80-100 fathoms (490-600 feet, or 145-100 meters). 

Meanwhile, the definition of the Continental Shelf according to UNCLOS 1982 lies in Article 76, which states that the Continental Shelf of a coastal country (archipelago country) includes the seabed and the land beneath it, from areas under sea waters that lie outside the territorial sea area, which is a natural extension or continuation of its land territory to the edge of the sea on the edge of the continent or up to a distance of 200 nautical miles from the baseline where the width of the territorial sea of ​​a coastal state is measured, and the outer edge of the edge of the continent may not exceed that distance. 

So, if you look back at the 1982 UNCLOS which discussed the Continental Shelf, there will definitely be provisions regarding the limits of the Continental Shelf in each country, namely in the form of:

  1. The seabed and subsoil outside the territorial sea to a depth of 200 meters, if it is used for the purpose of exploring and exploiting its natural resources.
  2. The seabed and subsoil beyond the depth limit of 200 meters to where technological capabilities can explore and exploit its natural resources.

Methods of Determining the Continental Shelf According to UNCLOS III 1982

The determination of the outer limits of the Continental Shelf stated in UNCLOS 1982 is in the form of:

  1. Based on the outermost fixed point, where the thickness of the sedimentary rock is at least 1% of the shortest distance between that point and the foot of the continental slope.
  2. 60 nautical miles from the foot of the continental slope.
  3. The outer limits of the Continental Shelf shall not exceed 350 nautical miles from the baselines from which the territorial limits are measured.
  4. The outer limit of the Continental Shelf does not exceed 100 nautical miles from the 2500 m depth line.

Well, geophysically, the seabed that borders the coast generally consists of 3 separate parts, namely the ” continental shelf “, ” continental slope “, and ” continental rise “. A little extra, how to measure the area of ​​the Continental Shelf depends on the continental configuration found in coastal countries (archipelago countries). Therefore, the coastal state may set the outer limits of the Continental Shelf differently around its territory.

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Continental Shelf Limits

Determination of Continental Shelf Limits

In determining the limit of the Continental Shelf, three conditions must be considered, namely:

  1. Determination of the limit of the Continental Shelf is less than 200 nautical miles. The outer limit of the Continental Shelf is 200 nautical miles or squeezed by the Exclusive Economic Zone (EEZ). This concept is called the Co-extensive Principle .
  2. Delimitation of the Continental Shelf of more than 200 nautical miles. The outermost boundary of the Continental Shelf refers to the 4 terms of the outer edge of the continental margin.
  3. Determination of the boundaries of the Continental Shelf which borders other coastal countries (archipelagic countries). The outer limits of the Continental Shelf refer to agreements between interested countries. This occurs when the distance between countries is less than 400 nautical miles. In order to determine the boundaries of the continental shelf in accordance with UNCLOS 1982, it is necessary to further understand the baselines, the toes of the continental slopes, the outer edges of the continental margins, and ridges .

Given these restrictions, a bathymetric measurement is required to obtain a depth line of 2,500 meters. After getting the depth line, compare it with the boundary 350 nautical miles from the base line, then choose the farthest limit of the Continental Shelf. In this case, each country is allowed to choose between these two criteria in order to get the maximum limit of the Continental Shelf.

a) Base Line

Based on UNCLOS 1982, the baseline is a starting line that connects the outermost points which are measured at the position of the low water line , where seaward boundaries such as the territorial sea and other marine jurisdictional areas can be measured. This area of ​​maritime jurisdiction can include the contiguous zone, the continental shelf, and the Exclusive Economic Zone (EEZ).

Thus, the baselines can be used as a reference in drawing the outer boundaries of these territorial waters. The baseline consists of several types, namely:

  • Normal baseline ( normal baseline )
  • Straight baseline ( straight baseline )
  • Baseline closing ( closing line )
  • Archipelagic baseline _

b) Continental Slope Leg

If you look at the physical appearance of the foot of the continental slope, you will definitely see the following characteristics:

  • A fold line ( joint line ) between two slopes or different surfaces.
  • A connecting line between two distinct crustal structures.
  • The upper surface represents the original structure of the continental margin crust.
  • The subsurface represents the sedimentary structure of the corresponding continental margin crust.
  • The top surface has a greater gradient than the lower surface.
  • Surface deposits (subsurface) are located near basins on the seafloor.
  • If there are more folds, then the deepest fold has the greatest probability as the foot of the intended continental slope.
  • The gradient change of the slopes can vary.

c) Determination of the outer margins of the continental margins

To determine the outer edge of the continental margin, it can be done using the sedimentary rock approach or commonly referred to as geological/geomorphological criteria and depth distance criteria. However, there are also restrictions regarding the outer edge of the coast of a coastal state (archipelagic country), which may not exceed 350 nautical miles from the baselines, or around 100 nautical miles from a depth line of 2,500 m.

Indonesian Continental Shelf

Previously, it was briefly described that our country is the largest archipelagic country in the world. Yep, Indonesia even has maritime boundaries with 10 neighboring countries, namely Australia, Timor Leste, Papua New Guinea, Palau, the Philippines, Vietnam, Thailand, Malaysia, Singapore and India. In arranging maritime boundaries with the 10 neighboring countries, according to the 1982 Convention on the Law of the Sea alias UNCLOS, Indonesia has the right to determine the outer boundaries of its various maritime zones. In setting the maximum limits, it can be calculated from the baseline which is then determined as follows:

  • Territorial sea ( territorial sea ), namely the zone part of the territory of the country as far as 12 nautical miles measured from the baselines.
  • Additional zone ( contiguous zone ) , where the state has special jurisdiction as far as 24 nautical miles from the baselines .
  • The Exclusive Economic Zone (EEZ), namely a zone where the state has sovereign rights to exploit its natural resources above the seabed to sea level and on the seabed and the land below, a distance of 200 nautical miles measured from baselines .
  • Continental Shelf, namely a zone where the state has sovereign rights to exploit natural resources on the seabed and the land beneath it: between 200 – 350 nautical miles (nautical mile ) or up to 100 nautical miles from a depth of 2,500 meters .

Well, in Indonesia, these boundaries will usually be given in the form of a list of geodetic coordinates in the form of a circle line and longitude.

Principles of Setting the Indonesian Continental Shelf

In terms of the Continental Shelf, Indonesia also has principles that must be considered. This principle is found in the Drafting of Academic Papers for the Draft Amendment/Replacement of Law Number 1 of 1973 concerning the Indonesian Continental Shelf, which includes:

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1. Principle of Archipelagic State

Since Indonesia is considered the largest archipelagic country in the world, our country also has principles based on the Archipelago Concept. This conception describes the perspective of the Indonesian people in seeing their own country which consists of thousands of islands and is surrounded by vast waters located around and between them.

In the Conception of Archipelagic Insight, sees the sea as a unifying island that is scattered from Sabang to Merauke by following the equator. Therefore, both land and sea as a territorial unit do not have different status from a legal perspective, even though in reality they are indeed different and separate.

Thus, the Archipelagic Insight Principle sees the Indonesian Archipelago as a unified territorial unit. This also includes all legal implications for parts of the ocean space located around the Indonesian Archipelago, starting from the water column, the seabed and the subsoil, as well as the natural wealth contained therein.

2. The Principle of Optimizing Natural Resource Management

Sinaumed’s needs to know that the relatively large potential of marine resources has not been fully explored and exploited, especially on the Continental Shelf, so it is still very likely to be utilized. Now, with international recognition of sovereign rights over the Continental Shelf, the Republic of Indonesia needs to establish policies for managing its natural resources on a broader scale.

After all, this principle also emphasizes obtaining economic benefits rather than emphasizing the amount of physical production ( physical yield ), as long as it implements optimal policies.

3. Principles of Sustainable Development

Although on the Continental Shelf it is permissible to explore and exploit existing resources, it still has to pay attention to the principle of sustainable development ( sustainable development ). Why so? So that the potential of existing resources can be utilized for the benefit of present and future generations.

Therefore, in order to explore and exploit the Continental Shelf, environmental sustainability must be considered, including through efforts to prevent pollution of the marine environment. So, to apply this principle, all the parties concerned also remind each other. The effective way is that if there are parties that cause marine pollution, they must be subject to administrative sanctions in the form of fines, criminal sanctions, and compensation for the costs of recovery.

4. The Principle of Respect for the Rights of Other Countries

The existence of the Continental Shelf in Indonesia is definitely bordered by other countries, therefore Indonesia itself must also guarantee the rights and freedoms of other countries guaranteed under the High Seas legal regime. In the event that the Indonesian Continental Shelf faces or adjoins the Continental Shelf of other countries, the boundaries are determined based on an agreement through negotiations.

5. Principle of Legal Certainty

Through the existence of this Continental Shelf regulation, it is hoped that it will be able to create legal certainty, especially in terms of the utilization of the Continental Shelf itself. Even the existence of the law can also invite private investors, both foreign and domestic.

6. Principles of Participation, Transparency and Accountability

Arrangements for the utilization of the Continental Shelf must be able to accommodate the participation of all interested parties in a transparent and accountable manner. Therefore, any data and information regarding the Continental Shelf should be open for public access, except for data and information related to state secrets and security.

7. Principle of National Interest

The utilization of potential natural resources on the Continental Shelf is solely intended to protect national interests, including the strategic interests of national defense and security. Licensing will only be granted if it is beneficial to national interests and does not endanger the safety and security of the State. The results obtained must also benefit the national economy, support development for the welfare of the entire Indonesian nation and open up the possibility of technology transfer.

So, that’s a review of the Continental Shelf in coastal countries, including Indonesia. Is Sinaumed’s interested in studying Indonesian Maritime Law?


Palupi, F. (2019). The existence of the continental shelf boundary line between Indonesia and Malaysia in Gosong Niger is viewed from international maritime law.


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