The regional bathymetric Atlantic – Channel – North-Sea DTM has a resolution of 0.001° (~111m). Its geographic coverage includes the Bay of Biscay, the English Channel and a part of the North Sea. The DTM extends from the coast to the continental slope (about of 4800m deep). This DTM is produced in the framework of the HOMONIM project which aims at improving operational forecast capabilities for the national coastal flood warning system. This DTM is offered openly on the Shom diffusion website (http://diffusion.shom.fr/produits/bathymetrie/mnt-facade-atl-homonim.html). http://dx.doi.org/10.17183/MNT_ATL100m_HOMONIM_WGS84

The DTM is a compilation of multibeam echosounder surveys acquired in 2013. The resolution is 1/64 arc-minutes (~30m). Surveys are located on the Capbreton Submarine Canyon (France) with depths from -4.7m to -344.9m. Depths are referenced to the Lowest Astronomical Tide and the coordinates are expressed into the WGS84 reference frame. The surveys which compose the DTM are S201306500-09 and S201306500-11. Data and metadata associated to these surveys are available on the website http://diffusion.shom.fr/pro/lots-bathy.html. The DTM is not to be used for navigation.

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : tidal range for mean neap tides for average atmospheric conditions..

Geographic information layer including the Limit of maritime affairs - mainland France, French Guiana, Martinique and Guadeloupe. This layer must be considered as an initial version to be validated locally by the competent services. Shom actively seeks out any information which could complete and improve the precision of this layer. The streams and rivers listed correspond to those mentioned in the applicable regulations and/or by a competent Government service. An inventory of existing legal and geographic information was drawn up prior to production in the form of an enquiry targeting services during the second half of 2014. The source legal text and a summary of digital conversion processes is available for each boundary proposed.Updated july 2018

This product includes the boundaries of tidal zones for French Channel, Atlantic and Mediterranean coasts in shapefile format. Information on the characteristics of tidal zones is available as part of the "Maritime Altimetric Reference Values" product.

The product "BathyElli surfaces v2.1" contains the surface realisation of the ellipsoidal height at the reference date of 1 January 2000 of the characteristic tidal levels corresponding to : - Highest Astronomical Tide (HAT): "BathyElli v2.1 HAT / ell" ; - Mean Sea Levels (MSL): "BathyElli v2.1 MSL / ell"; - Lowest Astronomical Tide (LAT): "BathyElli v2.1 LAT / ell"; - Chart Datum (CD) vertical sea level reference for each tidal zone: "BathyElli v2.1 HZ / ell".

Marine toponymy data layer obtained from French ENC and created using the S23 (4th edition, June 2002). Note: The usual Sea of Japan designation does not imply taking a stand in the dispute between Korea, which names this sea "East Sea", and Japan, which names it "Sea of Japan".

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 20 : minimum tidal range for average atmospheric conditions..

In accordance with decree no. n°2019-165 of 5 March 2019, Shom measures and updates maritime altimetric datums or hydrographic datums for French ports in mainland France and overseas administrative departments and authorities. These datums are provided to allow for standardisation based on legal altimetric datum systems (e.g. IGN69). Shom also disseminates typical tide figures for each port (lowest tide, mean tide, etc.). The Marine Altimetric Reference Value (RAM) product is available for ports in mainland France and for overseas territories with a tidal observatory.

The product contains a description of submarine cables and pipelines brought to the attention of Shom on French areas of responsibility. These are 2D linear objects of the seabed that divide into two categories: • The submarine cables: these are cables placed on the seabed where electricity or information (telecommunication) flows. They represent the vast majority of objects (more than 90%); • Emissaries and submarine pipes: these are pipes that allow the discharge, sampling or circulation of fluids.