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.

The Shom uses a 2D barotropic version of the HYCOM code (https://hycom.org/) to compute water level /surge forecasts (astronomical tides and meteorological surges) for the Atlantic, Mediterranean, Antilles-Guyane and Indian Ocean domains. The configurations use curvilinear grid with resolutions of several km offshore and ranging from 1.5km to around 500m on the french mainland coasts and the Antilles-Guyana coast. A downscaling by nesting allows a resolution of 800m to 200m over the Indian domain. These models have been adapted by the Shom to be operable in coastal areas by taking into account, in particular, the tide and high resolution bathymetry in these areas (from 100m for DTMs of facade to 20m for coastal DTMs) using Litto3D surveys by airborne LIDAR. The models are operated by Météo-France and the Shom in the framework of the HOMONIM project for the coastal flood/wave warning system.

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.

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..

RasterMarine is a series of digital images taken from nautical charts, with no additions, legends or georeferencing information. The RasterMarine range is available at six sets of scales: - RasterMarine10 1:10,000 - RasterMarine25 1:25,000 - RasterMarine50 1:50,000 - RasterMarine100 1:100,000 - RasterMarine350 1:350,000 - RasterMarine1M 1:1,000,000. Unless exceptional circumstances apply, the RasterMarine range is updated on a weekly basis and the modified grid squares are re-published, replacing the previous versions. All corrections, publications, editions and suppressions with an effect on the reference nautical charts are taken into consideration. <br /> 11/06/2026 version <br />

This product includes all Shom digital files for tidal currents on mainland French coasts (Channel and Atlantic coasts) in mesh format. These digital files indicate surface tidal current components, hour by hour and for two typical tidal coefficients (45 and 95) and maximum current speeds for a mean spring tide. Brest is taken as the reference port for viewing purposes. The current points included in these files correspond to the arrows shown on current atlases.

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.

Shom is the national referent for the level of the sea in situ on all areas under French jurisdiction. In this capacity, he assures under the acronym REFMAR different coordination functions in the collection and dissemination of public data related to water level observations, in order to promote their use in multiple applications within the framework of international recommendations.