Limit of 1 mile of the low sea mark — Metropole

The 1 mile limit of the low sea mark is built 1 mile downstream of the base line. This is the low-sea mark that can be assimilated to hydrographic zero, i.e. the normal base line out of areas where a straight base line is present. It is the default downstream limit of ‘Coastal waters’ within the meaning of the WFD. However, the downstream boundary of “Coastal Waters” may be extended offshore to encompass all “Transitional Waters”. The construction takes into account isolated benches, lighthouses, and turrets located outside the right base lines and less than 12 miles from the mainland or an island (elements used for the calculation of territorial waters: Chausez, Roches Dovers, Plateau de Cordouan). Source data are derived by calculation of elements contained in the SHOM databases: REGMAR (baseline), Lighthouses and beacons and BDBS (zero hydrographic). NB: Maritime Boundaries Guide: https://limitesmaritimes.gouv.fr/en-savoir-plus/le-contexte