Defining the Extended Continental Shelf

Steps in the delineation process 

The main steps for a coastal state in the process established by article 76 of the Convention are:

  • meeting the requirements of article 76 (see below) and preparing a submission showing the location of the outer limits of the continental shelf;
  • filing the submission with the Commission on the Limits of the Continental Shelf;
  • presenting the submission to the Commission and engaging with the Commission while it considers the submission;
  • receiving recommendations on the submission from the Commission;
  • undertaking necessary domestic steps, like promulgating regulations, to enact the coordinates (latitude/ longitude) of the outer limits; and
  • filing the coordinates of the outer limits with the United Nations.

Submissions can be very large. For example, some submissions filed by coastal states have weighed more than one tonne.  The process can also take many years.

What is not part of the delineation process

The Commission does not deal with areas under dispute and it does not delimit boundaries between coastal states. Delimiting boundaries is something that is done by states through negotiation or third party adjudication (eg: arbitration or submitting the matter to a court like the International Court of Justice or the International Tribunal for the Law of the Sea). 

Only the coastal state can determine its outer limits. The Convention provides that limits established by the coastal state on the basis of the Commission’s recommendations are final and binding.

Article 76 requirements: Formulae and constraints

Article 76 is an amalgam of scientific and legal concepts and can be confusing to both scientists and lawyers because it imbues scientific terms with a legal meaning distinct from their usual scientific meaning. Applying article 76 requires a significant amount of information about the shape and composition of the seabed which is obtained by collecting bathymetric and seismic data respectively.

The first thing a coastal state needs to do is locate the foot of the continental slope, which is usually where the maximum change in gradient occurs in a region called the base of the slope.

Then, the coastal state applies a combination of two formulae to determine how far out its shelf might go. These formulae are:

  • measure 60 nautical miles from the foot of the slope; or
  • determine where the sediment thickness is at least one percent of the distance to the foot of the slope (ie: depth ÷ distance ≥ 1%).

Next, the coastal state applies two constraints which curb the extent of the shelf. These are:

  • 2500 metre depth contour (also known as an isobath) plus 100 nautical miles; or
  • 350 nautical miles from coastal baselines [note: it is therefore possible for the shelf to extend beyond 350 nautical miles]

Finally, the coastal state determines the outer limits by following the formula line farthest from shore where the constraints are not exceeded and the constraint line farthest from shore where the formulae lines exceed the constraint.

Note: This is a simplified explanation of a complex process and is not exhaustive.