# Data licences and provenance

## OSM derived database — ODbL 1.0

© OpenStreetMap contributors. https://www.openstreetmap.org/copyright
The GeoJSON datasets in this directory are derived from OpenStreetMap and are distributed under the Open Database Licence 1.0: https://opendatacommons.org/licenses/odbl/1-0/
Individual data contents are governed by the Database Contents Licence: https://opendatacommons.org/licenses/dbcl/1-0/
Source: Overpass API, geographic selection 43.55,15.1,44.15,16.05, snapshot 2026-10-09T01:41:31Z. Coastline assembled into clipped land polygons; area objects converted to representative points where appropriate; original seamark tags retained. Some closed coastline way names become label points. Derived data are offered in full in this package and via download links in the application.

## EMODnet rendered bathymetry overview — CC BY 4.0

This data product was created by EMODnet (https://emodnet.ec.europa.eu/en/), is owned by the EU and licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence: https://creativecommons.org/licenses/by/4.0/
Source service https://ows.emodnet-bathymetry.eu/wms ; requested on 2026-10-09. Layers emodnet:mean (style atlas_land) and emodnet:contours, EPSG:3857. Image cropped to the geographic bounds above, displayed with opacity and separate OSM land overlays. This is a rendered overview, not full-resolution ENC or a numerical depth database. NOT FOR NAVIGATION.
Service and data terms: https://emodnet.ec.europa.eu/en/terms-use-emodnet-online-services-data-and-data-products

Dataset counts are not a statement of real-world completeness. No route, safe depth or navigability is inferred.

## EMODnet numerical grid and model-derived layers — CC BY 4.0

EMODnet Bathymetry DTM 2024, regional `elevation` grid exported from https://erddap.emodnet.eu/erddap/griddap/bathymetry_dtm_2024.html on 2026-10-09. Original elevations negated to show model depth, encoded at 0.1 m numeric steps; numeric encoding is NOT a claim of 0.1 m accuracy. Approximate native angular cell size 1/960 degree. Source vertical reference LAT. Sparse labels, model contours and <=5 m cell overlay are derived from this numerical model. This data product was created by EMODnet, is owned by the EU and licensed under CC BY 4.0. NOT FOR NAVIGATION.

The experimental routing mask combines this grid with the included ODbL OSM-derived land and hazard database and is supplied under ODbL, preserving both sources and their attribution. Masking and buffering do not establish completeness or safe navigability.

The stored route-mask retains its original 200 m coast / 250 m hazard / 100 m restricted-area bands as derived context for display and local refinement. Version 4 routing does not treat those broad bands as hard exclusions when exact OSM geometry is available. It checks the original coast polygons and mapped obstacle points / source way footprints with an experimental 25 m geometric margin; unknown depth is displayed separately. Finer routing geometry does not increase bathymetric resolution.