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.

This study provides an initial global estimate of the extreme water level values along the French metropolitan coastline. These results are to be refined locally with all available data and knowledge. The method used is based on a statistical analysis of the tide gauge observations available in the ports. It does not take into account wave observations. The results between ports are obtained by an interpolation method. The study produces at the reference ports the statistical estimates: - extreme values of high water surge in the Channel and Atlantic; - extreme values of water level for the whole of Metropolitan France. And a set of statistical estimation maps of extreme water level values along the coastline. The estimates provided go up to the 1,000-year return period. In view of the duration of observations used at the ports, the user must check whether estimates with a return period of more than 50 or 100 years are still valid 50 or 100 years still make sense.

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.

Litto3D® marine part is a unique and continuous land-sea database which can provide 3D models of the shape and location of french coastal terrain. Surveys are carried out by airborne lidar bathymetry over the sea side and airborne lidar topography over the land side up to 400m inland. Litto3D® marine part digital models are available in two formats: a set of 3D points and a qualified terrain mesh. The partial product "Litto3D® marine part - Nouvelle-Aquitaine 2020-2022" covers the geographical area from the Sèvre Niortaise to the Ile d'Oléron and from the Gironde estuary to the Spanish border. It will be updated as treatment progresses. Eventually, the entire Nouvelle-Aquitaine coastline will be covered.

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

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

<strong>This data is not up to date with the order dated 30 August 2021 amending the order dated 23 November 1987 on ship safety, which now raises the limit for category 4 ships to 5 miles from the nearest coast.</strong> The navigation category allocated to a ship is indicated on its shipping license, together with any applicable restrictions. This limit was produced by Shom in application of section II.14 of article 1 of decree no. 84-810 amended on 30 August 1984. Navigation categories are defined in article 110.10 of the rules appended to the order of 23 November 1987 on shipping safety.

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.

The "Military practice areas" product contains vector data in the form of 2D surface objects describing the military practice areas in the France sector represented on Zonex variants of nautical charts. This is the S-57 MIPARE object class (military practice areas): maritime zone within which military, naval or air exercises can take place.

The coastal topo-bathymetric DTM of the Arcachon basin and its surroundings at a resolution of 0.0002° (~ 20 m) was produced as part of the HOMONIM project. The DTM covers the coastline of a part of the Gironde department, from the Carcans and Hourtin ponds in the North, to the Cazaux and Sanguinet lakes in the South. It covers the entire Arcachon basin and extends offshore to about 40 m depth. The DTM is intended to be implemented in hydrodynamic models in order to produce accurate forecasts of water heights and sea states at the coast and to improve the French storm surge warning system. This product is available with the Lowest Astronomic Tide (LAT) or with the Mean Sea Level (MSL) as a vertical datum.