When a country wishes to extend the surface of its legal continental shelf beyond the normal 200 nautical miles, it must submit an application to the Commission on the Limits of the Continental Shelf (CLCS), a specific United Nations Commission. An extension can be claimed as long as the seabed meets the criteria of being a natural prolongation of a State's land mass, with geological and morphological continuity.

To prepare the application in compliance with these criteria, in 2002, France set up a dedicated programme called EXTRAPLAC (EXTension RAisonnée du PLAteau Continental — Annotated Extension of the Continental Shelf), coordinated by the Secretary-General for the Sea. IFREMER is in charge of the scientific and technical aspects of the application, along with the avec le French National Hydrographic Service (SHOM), IFP Énergies nouvelles and the French Polar Institute Paul-Emile Victor (IPEV). These organisations provide the scientific expertise and the naval resources required for completing the French application.

The role of IFREMER

To study the geological and morphological characteristics of the deep seabed, IFREMER can make use of

  • unique scientific expertise,
  • naval resources (vessel fleet), exploration equipment (digital rapid-deployment seismometers; multi-beam sounders, gravimeter, magnetometer), sampling equipment (corers, dredgers) and data processing resources (on-board software Caraibes)


EXTRAPLAC has several tasks: acquisition of measurements at sea, analysis of geophysical data, preparation and submission of applications, follow-up of the application review by the CLCS. Since the first submission in 2006, the EXTRAPLAC programme has prepared and submitted applications for 11 areas of the French maritime domain.

After the review of the first applications submitted between 2006 and 2009, France received recommendations from the CLCS on the outer limits of its continental shelf beyond 200 nautical miles. The areas covered by these extensions include French Guiana, Martinique, Guadeloupe, New Caledonia, Kerguelen Islands, covering a total surface area of 579,000 km². French maritime territories around the world.

The economic stakes behind EXTRAPLAC

The extension of the continental shelf is above all an economic issue. Each coastal country has a maritime space that stretches 200 nautical miles (nmi) (around 370 km) from the coast: this is called the Exclusive Economic Zone (EEZ). The country has sovereign rights in this zone and can explore and use the resources from the sub-seabed and its adjacent waters.

According to Article 76 of the United Nations Convention for the Law of the Sea of 1982, a coastal state can extend the continental shelf under its jurisdiction beyond the limit of 200 nautical miles. This extension — of up to 350 nmi (650 km) — involves only the continental shelf, i.e. the seabed and the subsoil of the submarine areas that constitute the natural prolongation of the terrestrial land mass, with waters remaining in the international domain. It differs from the EEZ, which includes the water column.

In these areas of the continental shelf, the Convention grants coastal states sovereign rights to explore and use the natural marine resources found on the seabed and in its subsoil. Oil and gas, minerals, metals or biological resources: the potential resources of these new unexplored areas constitute future challenges for States and scientists.

The Convention also allows countries to share the resources of the continental shelf beyond the 200 nautical miles with signatory countries, particularly developing countries or those that are landlocked.

Scientific and environmental issues

The exploration of the deep sea is essential to understand them better and to study their evolution. The active geological and geochemical processes that act in the concentration of ores are also those that produce the energy required to support life in the deep sea. In the absence of light, all life is based on chemosynthesis. Exploration provides precious information on these vast unknown areas, improve understanding of biodiversity and help define protection strategies.