School of Surveying and Spatial Information Systems

The University of New South Wales

Technical Aspects of Extended Continental Shelf Claims:

A Case Study of the Rockall Plateau

by Brendan Irwin

Supervised by C. Schofield

October 2004


There are currently 117 of the 151 Coastal States that are party to the 1982 United Nations Convention on the Law of the Sea (the Convention). The Convention regulates the delimitation of maritime boundaries and the use of the ocean's resources throughout the international maritime community. The outer limit of the zone potentially furthest seaward of which a State may claim under the rules of the Convention is the continental shelf. The aim of this thesis was to analyse the technical aspects of extended continental shelf claims which included a study of  the Convention and the Commission on the Limits of the Continental Shelf and the various topics of interest associated with these bodies such as baselines, islands and rocks, the continental shelf and dispute resolution.

Continental Shelf

“The continental shelf of a coastal State comprises the sea-bed and subsoil of the submarine area that extends beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured where the outer edge of the continental margin does not extend up to that distance" (Article 76, paragraph 1 of the Convention). Figure 1 illustrates the various limits for the continental shelf and its extension beyond 200 nautical miles.

Figure 1: The Continental Shelf (Carleton and Schofield 2001 Fig.30, p.64)

States who believe that their continental shelf extends beyond 200 nautical miles may lay claim to this extended area upon meeting specific criteria. This area beyond 200 nautical miles is known as the extended continental shelf with the major driving force for delimitation being resource exploitation. There lies approximately 15 million km² of potential continental shelf beyond the 200 nautical mile limit, to which sovereign rights may extend to under the rules of the Convention. Up to 54 coastal States may be able to claim for their extended continental shelf.

Rockall Case Study

The Rockall Plateau is subject to multiple and extensive overlapping claims to maritime space involving Denmark, Iceland, Ireland and the United Kingdom as seen in Figure 2. When the claims are superimposed there are two large areas of trilateral overlap (Denmark/Iceland/UK and Denmark/Ireland/Iceland) and three areas of bilateral overlap (Denmark/Iceland, Ireland/Iceland and Iceland/UK) (Claims to Maritime Space).

Figure 2: Competing Claims in the Rockall Area (Schofield and Pratt 2000)

The Rockall case study involved the collection and analysis of the legislation of the four States and any existing maritime agreements that may have significance on the disputed area. A geophysical study of the Rockall area was undertaken by Hinz and van de Poll and was quite comprehensive. This study was used together with the legislation, agreements, analysis of the Convention and the Commission on the Limits of the Continental Shelf and an analysis of the various international dispute settlement techniques.


There are many methods that can be used for dispute resolution which are based on certain considerations. These include; coastal, political, strategic, historical, legal regime and other geographical considerations such as the use of islands, rocks, reefs and low-tide elevations. The most practical method in my opinion after analysing the Rockall Plateau, the Rules of the Commission and the structure of the Convention would be to present a joint submission to the Commission defining the area that would not prejudice on the delimitation of maritime boundaries between the States.

Once an area has been specified defining the outer limits of the continental shelf beyond 200 nautical miles it must be divided up between the four States. The area should look to be divided up in a way that is equitable to all the States and most importantly is practical in relation to resource exploitation and management. A method that could achieve this could be to create a joint development zone or zones of the area beyond 200 nautical miles. It has advantages over that of the median line or another form of calculated boundary, “the focus would be placed where it belonged: on a fair division of the resources at stake, rather than on the determination of an artificial line, thus, eliminating competition over the ownership of resources...especially where the resources are unknown”. The last line of this quotation (Richardson 1988, p.451-452) is especially relevant to the Rockall case study as it is unknown as to the resource supply in the area due to the deep offshore drilling that would be required. If a joint development zone is to be created over the continental shelf beyond 200 nautical miles in the Rockall Plateau area, it will be required to be divided up into four percentages in terms of resource exploitation. 

There are many dispute resolution techniques mentioned in this thesis that could be used to accompany the negotiations required for a joint development zone or another form of solution. The majority of the methods were created on the basis of the States retaining control of the dispute and managing its resolution technique and so it would be in their best interests to use those methods. Once an agreement has been achieved by the four States and the result is binding, the outer limits of the continental shelf and the new maritime boundaries must be officially published in order for clarification to the rest of the International maritime community.


Carleton, C and Schofield, C, 2001. Developments in the Technical Determination of Maritime Space: Charts, Datums, Baselines and Maritime Zones, Maritime Briefing Volume 3 Number 3 page 64

Pratt, M and Schofield, C, 2000. Cooperation in the Absence of Maritime Boundary Agreements: The Purpose and Value of Joint Development, page 153

Richardson, E, 1988. Jan Mayen in Perspective, pages 451-452

United Nations Convention on the Law of the Sea, [online] 2004,, page 49

Further Information

For more information, please contact 


Dr Clive Schofield (Supervisor)




School of Surveying and Spatial Information Systems

University of New South Wales




Phone: +61-2-9385-4174

Fax: +61-2-9313-7493