Bathymetric datasets, collected before 1970, are historical surveys acquired with leadlines (and single-beam echosounders after 1930-1940). Quality controls and qualification, conducted by the Shom, on these datasets are not exhaustive. Datasets may present significant uncertainties and errors may remain.

Litto3D is a unique and continuous land-sea database which can provide 3D models of the shape and location of French coastal terrain. A line separates sea and land data acquisition zones, and the associated survey readings obtained using bathymetric lidar technologies or multibeam echosounders for sea readings and airborne lidar topographical surveys for land readings, with 300 m overlap. Litto3D digital models are available in two formats: a set of 3D points and a qualified terrain mesh.

Litto3D provides 3D, continuous sea-land description of French coastal areas. Data is acquired by airborne topo-bathymetric LiDARs. Litto3D products come in 3D point clouds and digital terrain models formats. The product "Litto3D - Nouvelle-Aquitaine 2020-2022" covers the geographical area from the Charente-Maritime to the Spanish border. For the maritime part, the data produced by Shom extend offshore down to signal extinction, approximatively 20 depth when environmental conditions are optimal. On land, the data are truncated at a limit that ensures the product retain its coastal character.

The bathymetric DEM of Tahiti and Moorea with a resolution of 0.001° (~ 100 m) was produced by the Shom for Météo-France (Inter-regional Direction in French Polynesia). This DEM covers a 10 km radius around the islands of Tahiti and Moorea in order to meet the need for marine submersions modelling in French Polynesia. This product is available at different vertical references, either the lowest astronomical tide (LAT) or the mean sea level (MSL).

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 coastal topo-bathymetric DEM was produced using the bathymetric and topographic data acquired between 2012 and 2015 by Shom and the PASSION programme team. The 20 m coastal grid covers the Passion atoll – Clipperton and the local flanks of the atoll to a depth of 1500 m. Passion island - Clipperton, in the eastern Pacific Ocean, is a remote uninhabited atoll over 5,000 km from Tahiti in French Polynesia and over 1,000 km from the Mexican coasts. Passion island is the highest point on the Clipperton ridge, and the only location above water level. This is the only coral atoll in the eastern Pacific in the northern hemisphere, at a longitude of W 109° and a latitude of N 10°.

The coastal topo- bathymetric DEM for the coasts of Morbihan with a resolution of 0.0002° (~ 20 m) was prepared as part of the TANDEM project (Programme Investissements d'Avenir, ANR-11-RSNR-00023-01). It covers the French administrative department of Morbihan and part of Loire-Atlantique. This DEM runs from the Gâvres peninsula in the north west to La Baule in the south east and covers the Gulf of Morbihan, the Quiberon bay and peninsula, Houat, Hoëdic and Belle-Ile islands and the Vilaine estuary. The DEM is designed to be implemented in the hydrodynamic models of the TANDEM project in order to estimate the coastal effects of tsunamis for the Atlantic and English Channel, where French nuclear power plants have been installed for about 30 years. This product is available with the Lowest Astronomic Tide (LAT) or the Mean Sea Level (MSL) as a vertical datum.

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. The vertical reference for this product is Mean Sea Level (MSL).

Bathymetric datasets, collected between 1970 and 1990, are mainly acquired with single-beam echosounders. Quality controls and qualification, conducted by the Shom, on these datasets are not exhaustive. Datasets may present significant uncertainties and errors may remain.

The bathymetric DEM for the coasts of Guadeloupe and Martinique with a resolution of 0.001° (~ 100 m) was prepared as part of the HOMONIM project. The DEM covers some of the Lesser Antilles islands, from Montserrat in the north to Sainte-Lucie in the south. The model ranges off-shore to a depth of 5800 m. The DEM is designed to be used in hydrodynamic models in order to produce high-precision forecasts for coastal water levels and sea conditions and therefore improve the pertinence of the Waves-Submersion monitoring programme.