The land-sea limit corresponds to the Highest Astronomical Tide (HAT) in the case of a tide of coefficient 120 and under normal meteorological conditions (no offshore wind and mean atmospheric pressure of 1013 hPa). This geometric line is naturally defined as the intersection of a HAT model (extended to the coast and the top end of the upper estuary) based on the available Bathyelli surfaces, and a high-resolution digital terrain model of the coastal area. It corresponds to the highest limit of the intertidal area and takes into account, when they exist, the 3 administrative maritime limits which are: the transversal limit of the sea (LTM), the salt water limit (LSE) and the limit of maritime jurisdiction (LAM). This limit is measured (quoted) in relation to the local hydrographic chart datum and to the levels of reference for France (IGN69 and IGN78 for Corsica). Relations to other levels of reference (mean sea level and ellipsoid) are known. The land-sea limit product, mainly results from the exploitation of the two products Litto3D®/RGEALTI® and Bathyelli, and represents, with a metric resolution (1 to 5 metres), this theoretical entity by a set of 2D polylines describing the nature of the coast (artificial or natural, rocky or sandy, steep or flat, etc.). The method used for calculating the land-sea limit makes it possible to produce a continuous, homogeneous and spatially coherent limit on the entire French metropolitan coastal area.

The "EMODnet Digital Bathymetry (DTM)- 2022" is a multilayer bathymetric product for Europe’s sea and oversea basins covering: • the Greater North Sea, including the Kattegat and stretches of water such as Fair Isle, Cromarty, Forth, Forties,Dover, Wight, and Portland • the English Channel and Celtic Seas • Western Mediterranean, the Ionian Sea and the Central Mediterranean Sea • Iberian Coast and Bay of Biscay (Atlantic Ocean) • Adriatic Sea (Mediterranean) • Aegean - Levantine Sea (Mediterranean). • Madeira and Azores (Macaronesia) • Baltic Sea • Black Sea • Norwegian and Icelandic Seas • Canary Islands (Macaronesia) • Arctic region and Barentz Sea and the Caribbean Sea. The DTM is based upon 21937 bathymetric survey data sets and Composite DTMs that have been gathered from 64 data providers from 28 countries riparian to European seas and beyond. Also Satellite Derived Bathymetry data products have been included fro Landsat 8 and Sentinel satellite images. Areas not covered by observations are completed by integrating GEBCO 2022 and IBCAO V4. The source reference layer in the portal viewing service gives metadata of the data sets used with their data providers; the metadata also acknowledges the data originators. The incorporated survey data sets itself can be discovered and requested for access through the Common Data Index (CDI) data discovery and access service that in December 2022 contained > 41.000survey data sets from European data providers for global waters. The Composite DTMs can be discovered through the Sextant Catalogue service. Both discovery services make use of SeaDataNet standards and services and have been integrated in the EMODnet portal (https://emodnet.ec.europa.eu/en/bathymetry#bathymetry-services ). In addition, the EMODnet Map Viewer (https://emodnet.ec.europa.eu/geoviewer/ ) gives users wide functionality for viewing and downloading the EMODnet digital bathymetry such as: • water depth (refering to the Lowest Astronomical Tide Datum - LAT) in gridded form on a DTM grid of 1/16 * 1/16 arc minute of longitude and latitude (ca 115 * 115 meters). • option to view depth parameters of individual DTM cells and references to source data • option to download DTM in 58 tiles in different formats: ESRI ASCII, XYZ, EMODnet CSV, NetCDF (CF), GeoTiff and SD • option to visualize the DTM in 3D in the browser without plug-in • layer with a number of high resolution DTMs for coastal regions • layer with wrecks from the UKHO Wrecks database. The EMODnet DTM is also available by means of OGC web services (WMS, WFS, WCS, WMTS), which are specified at the EMODnet Bathymetry portal. The original datasets themselves are not distributed but described in the metadata services, giving clear information about the background survey data used for the DTM, their access restrictions, originators and distributors and facilitating requests by users to originator.

The "EMODnet Digital Bathymetry (DTM)- 2024" is a multilayer bathymetric product for Europe’s sea and oversea basins covering: • the Greater North Sea, including the Kattegat and stretches of water such as Fair Isle, Cromarty, Forth, Forties,Dover, Wight, and Portland • the English Channel and Celtic Seas • Western Mediterranean, the Ionian Sea and the Central Mediterranean Sea • Iberian Coast and Bay of Biscay (Atlantic Ocean) • Adriatic Sea (Mediterranean) • Aegean - Levantine Sea (Mediterranean). • Madeira and Azores (Macaronesia) • Baltic Sea • Black Sea • Norwegian and Icelandic Seas • Canary Islands (Macaronesia) • Arctic region and Barentz Sea and the Caribbean Sea. The DTM is based upon 22063 bathymetric survey data sets and Composite DTMs that have been gathered from 66 data providers from 28 countries riparian to European seas and beyond. Also Satellite Derived Bathymetry data products have been included from Landsat 8 and Sentinel satellite images. Areas not covered by observations are completed by integrating GEBCO 2024 and IBCAO V4. The source reference layer in the portal viewing service gives metadata of the data sets used with their data providers; the metadata also acknowledges the data originators. The incorporated survey data sets itself can be discovered and requested for access through the Common Data Index (CDI) data discovery and access service that icontains > 41.000 survey data sets from European data providers for global waters. The Composite DTMs can be discovered through the Sextant Catalogue service. Both discovery services make use of SeaDataNet standards and services and have been integrated in the EMODnet portal (https://emodnet.ec.europa.eu/en/bathymetry#bathymetry-services ). In addition, the EMODnet Map Viewer (https://emodnet.ec.europa.eu/geoviewer/ ) gives users wide functionality for viewing and downloading the EMODnet digital bathymetry such as: • water depth (refering to the Lowest Astronomical Tide Datum - LAT) in gridded form on a DTM grid of 1/16 * 1/16 arc minute of longitude and latitude (ca 115 * 115 meters). • option to view depth parameters of individual DTM cells and references to source data • option to download DTM in 59 tiles in different formats: ESRI ASCII, XYZ, EMODnet CSV, NetCDF, GeoTiff, RGB and SD • option to visualize the DTM in 3D in the browser without plug-in • layer with a number of high resolution DTMs for coastal regions • layer with wrecks from the UKHO Wrecks database. The EMODnet DTM is also available by means of OGC web services (WMS, WFS, WCS, WMTS), which are specified at the EMODnet Bathymetry portal. The original datasets themselves are not distributed but described in the metadata services, giving clear information about the background survey data used for the DTM, their access restrictions, originators and distributors and facilitating requests by users to originator.