Data sources and credits

Mermaid is built on the work of public agencies, open-data programmes and open-source communities. This page acknowledges the providers whose data and software make the product possible and the licences under which their work is used. Where a licence requires attribution, the notices below are the operative attribution statements for all Mermaid surfaces: the website, the skipper apps, the Crew web app, Mermaid Base and generated map bundles.

1. Places, harbours and facilities

OpenStreetMap

Harbour, marina, fuel-dock and facility information, and the land and road rendering on this website, include data © OpenStreetMap contributors, available under the Open Database Licence (ODbL) 1.0 (opendatacommons.org/licenses/odbl). OpenStreetMap data enriches harbour facility details (fuel, water, electricity, showers, contact channels) and corroborates charted places. Derived databases containing OpenStreetMap data remain subject to the ODbL share-alike terms.

Community contributions

Reviews, observations and confirmations contributed by Mermaid skippers and crews are used under the Terms and Conditions and the Community Policy. Aggregated signals are anonymised; individual contributors are not affiliated with, and do not endorse, Mermaid.

2. Charts and bathymetry

Copernicus and the European Space Agency

Satellite-derived bathymetry products contain modified Copernicus Sentinel-2 data (2024 to 2026), processed by Mermaid. Copernicus Sentinel data is provided free of charge by the European Union's Copernicus programme, operated by ESA.

NASA

Bathymetry calibration uses ICESat-2 ATL24 photon bathymetry data provided by NASA and distributed by the National Snow and Ice Data Center (NSIDC).

GEBCO

Regional depth context uses the GEBCO Gridded Bathymetry Data (GEBCO Compilation Group) under its public usage terms.

Official charts

Mermaid-derived chart and depth layers are planning aids and are not for primary navigation. The charts and publications of the national hydrographic offices remain the authoritative navigation products.

3. Weather

ECMWF

Forecast fields are based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF), used under the ECMWF open-data licence (CC BY 4.0). Neither ECMWF nor any data originator endorses Mermaid.

DHMZ, ALADIN-HR

Izvor podataka: Državni hidrometeorološki zavod (DHMZ), ALADIN-HR. ALADIN-HR forecast data (meteo.hr) is used under CC BY 4.0, subset, resampled and fused by Mermaid; gust magnitude is derived from the provider's vector components (cell-mean hourly maximum, 3-hour maxima beyond +24 h).

Agenzia ItaliaMeteo and ARPAE

High-resolution forecasts over Italy and the Adriatic use the ICON-2I model, produced by Agenzia ItaliaMeteo with ARPAE Emilia-Romagna and released as Italian open data (CC BY 4.0).

Copernicus Marine Service

Sea-state and marine fields use E.U. Copernicus Marine Service information; neither the European Commission nor Mercator Ocean is responsible for any use made of it.

Open-Meteo

Selected aggregated forecast tiers are retrieved through the Open-Meteo API (open-meteo.com) under CC BY 4.0.

4. Open-source software and fonts

Mermaid ships with and relies on open-source software including MapLibre GL (BSD-3-Clause), the Martin tile server (MIT / Apache-2.0), tippecanoe (BSD-2-Clause), GDAL (MIT/X), PostGIS (GPL-2.0) and the Flutter, Preact, Astro and Go ecosystems. Full licence texts are distributed with the respective packages. This website uses the Hanken Grotesk typeface (SIL Open Font License 1.1) and Google's Material Symbols (Apache License 2.0), both served from our own domain.

5. Trademarks and non-affiliation

Provider names are used solely to attribute data origin as the applicable licences require or recommend. The providers listed here do not sponsor or endorse Mermaid, and no affiliation is implied. Questions about attribution: info@mermaid.navy.