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.

Information layer containing the SAR Zones (Search and Rescue). This layer contains a description of the French search and rescue (SAR) areas and the location of the associated Maritime Rescue Coordination Center (MRCC). it covers the areas of responsibility of France. The layer was produced by the Shom pursuant to the Circular Circular of the International Maritime Organization (IMO No. SAR.8 / Circ.4 of 1 December 2012).

Wave forecasting models allow the representation of sea states based on a spectral resolution at the global scale or at the scale of ocean basins. This code calculates the evolution of the sea state by decomposing it into a wave spectrum that propagates in different directions and with different periods. During the propagation, the wave energy is increased or decreased by the effects of wind, breaking waves and energy exchanges between the different components. The wave forecasts available on data.shom.fr are calculated with 2 different types of models: MFWAM for the offshore domain (resolution from 0.5° to 0.1°) and Wavewatch III ® (WW3) for the coastal domain (resolution from 2' to 200m). MFWAM is a sea state forecasting model (wind wave and swell) derived from the third generation WAM code (WAMDI Group, 1988). Wavewatch III ® (WW3) is developed in a collaboration between the United States Weather Service (NOAA/NCEP), Shom, the University of Darmstadt in Germany, and other partners. The forecasts published on data.shom.fr are issued from the parameterization carried out and optimized by the Shom and Météo-France within the framework of the Homonim project (national coastal flood/wave/storm warning system).

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.

These maps are prepared on the basis of vector-based mapping data (IHO S-57 format) including the detailed description of each object (beacons, wrecks, submarine cables, regulated zones, survey systems, etc.). These maps are the digital equivalent of printed nautical charts.

Bathymetric datasets are an extraction of surveys belonging to the Shom public database. For depth up to 50m, the vertical precision of soundings varies from 30cm to 1m and the horizontal precision varies from 1 to 20m. In deep ocean, the vertical precision is mainly around 1 or 2% of the bottom depth. It is sometimes more, it depends on the technology used. The data are referenced to ZH which is assimilated to LAT. Data are corrected for sound velocity variations. <br /> October 27 2025 version

The update of the coastal topo-bathymetric DEM of the Pertuis charentais at a resolution of 0.0002° (~ 20 m) was carried out in the third phase of the HOMONIM project. The DEM extends from the terrestrial domain to about 60 meters depth over all the pertuis (pertuis Breton, pertuis d’Antioche and pertuis of Maumusson). The DEM is intended to be implemented in hydrodynamic models in order to produce forecasts as accurate as possible of water heights and sea states at the coast to improve the relevance of the Wave-Submergence Vigilance. This product is available with either the Lowest Astronomic Tide (LAT) or the Mean Sea Level (MSL) as a vertical reference.

The product "Sea bed sediment 1:50 000" contains 2D surface objects geo-referenced digital data describing the nature of the geological seabed (nature of the sediment, including rock type seabed).

This product shows the international distribution of types of tides. Four types of tides exist, and are classified based on the number and height of high and low waters each day: semi-diurnal tide: two high tides and two low tides with approximately the same height are recorded each day. Mixed tides with diurnal inequality: two high and low tides are recorded daily (just like with semi-diurnal tides), however the heights of the high and low waters vary significantly over the same day. Diurnal tides: one single high tide and one single low tide are recorded each day. Composite: tides can be diurnal or semi-diurnal or mixed.