The continental shelf (CS) designates the seabed and its subsoil beyond the territorial sea throughout the entire natural prolongation of the land territory, or to a distance of 200 nautical miles from the baselines .
To avoid all confusion, it should be noted that the legal definition of the continental shelf as established by the UNCLOS is independent of its geophysical definition and the eco-sysyems characterizing it. Up to a distance of 200 nautical miles, the UNCLOS thus recognizes a CS for any coastal state, even if it were entirely deprived of such a CS from a geophysical or oceanographic point of view. [Fig. 3]
The continental shelf and Exclusive Economic Zone (EEZ) share this maximum extent of 200 nautical miles in common (including the territorial sea). Therefore, when it is created, an Exclusive Economic Zone includes the continental shelf, whereas, in the absence of an EEZ, the coastal State's CS exists in any case, in immanent fashion . A specific legal regime follows on from this, distinguishing it from the EEZ: if an EEZ is to be declared, sovereign rights over the CS exist independently of any proclamation. A State therefore disposes of a continental shelf without, in a way, being obliged to say so (while on the other hand, it is obliged to create an EEZ off its coasts if it wants to exercise the sovereign rights and jurisdiction to which it is authorized by the Convention).
Thus, if an area not established as an EEZ by the coastal State is governed by the legal regime of the high sea, its sovereign rights over the CS are in any case exclusive . In the case of the Mediterranean: as the distance between the baselines of States opposite each other is in all cases less than 400 nautical miles, the legal regime which applies in the absence of an EEZ is that of the high sea, even if, everywhere, the seabed and subsoil form part of the continental shelf (cf. Area).
 UNCLOS, article 76, 1. As compared with the Geneva Convention of 1958 on the CS, that of 1982 modifies the definition criteria by replacing depth (200 metres) or exploitability by distance out at sea.
 This autonomy of the CS crops up again in the case of its extension beyond 200 nautical miles: if such an extension is possible, the coastal State disposes of a CS (and sovereign rights over natural resources for the purposes of their exploration or exploitation), even if the water column beyond this limit is covered by the legal regime of the high sea.
The UNCLOS introduced this possibility for extension but, to avoid unjustified extensions, it also set up a procedure and a specific institution responsible for reviewing such requests. The Commission on the Limits of the Continental Shelf (CLCS), with 21 members elected for 5 years by the Party States in their capacity as scientific experts, examines and investigates the applications submitted; it makes recommendations accepting, modifying or rejecting requests for extension.
The extended CS must correspond to specific scientific and technical criteria that the CLCS has developed since the 1982 Convention, in particular its article 76 in a manual entitled Scientific and Technical Guidelines which was adopted in May, 1999.
This procedure does not apply to the Mediterranean which is not eligible for any case of extension of the CS, as no part of it extends beyond the limit of 200 nautical miles. However, France, Spain and Morocco, which have double façades, have undertaken extension operations in the Atlantic.
Rights of the coastal State over the continental shelf.
1. The coastal State exercises over the continental shelf sovereign rights for the purpose of exploring it and exploiting its natural resources.
2. The rights referred to in paragraph 1 are exclusive in the sense that if the coastal State does not explore the continental shelf or exploit its natural resources, no one may undertake these activities without the express consent of the coastal State.
3. The rights of the coastal State over the continental shelf do not depend on occupation, effective or notional, or on any express proclamation.
4. The natural resources referred to in this Part consist of the mineral and other non-living resources of the seabed and subsoil, together with living organisms belonging to sedentary species, that is to say, organisms which, at the harvestable stage, either are immobile on or under the seabed or are unable to move except in constant physical contact with the seabed or the subsoil.