# Map data and attribution

**Reef charts, traced legs and the reef-warning layer** are derived from **OpenStreetMap** data. © OpenStreetMap contributors. OpenStreetMap data is available under the Open Database License (ODbL 1.0): https://www.openstreetmap.org/copyright

The derived databases this app ships (the reef grids for French Polynesia, Fiji and Tonga, the traced lagoon and pass legs, the coarse reef-warning cells, generated 2026-10-19, and the world tier's 0.01° land layer from OpenStreetMap's land polygons) are offered under the same ODbL 1.0 licence: https://opendatacommons.org/licenses/odbl/1-0/. Download them from the "Ava reef and leg database" page linked in Settings > About. They are a route-planning aid built from community map data: they are not a chart and not a navigation aid, and OpenStreetMap's reef coverage is uneven.

**Land mask (world tier):** OpenStreetMap land polygons at 0.01° (ODbL, above), with Natural Earth's 0.1° mask (public domain) for the plan's ends and where a block is missing.

**Time zones:** timezone-boundary-builder (ODbL 1.0), derived from OpenStreetMap, © OpenStreetMap contributors.

**Forecasts:** Open-Meteo (CC BY 4.0), with ECMWF, NOAA GFS and Météo-France model data; **typical conditions:** contains modified Copernicus Climate Change Service information (ERA5), via Open-Meteo. **Tropical cyclone tracks:** ECMWF open data (CC BY 4.0), model forecast, not a warning; NOAA NHC / CPHC (public domain). **Earthquakes:** USGS. **Disaster alerts:** GDACS (awareness only). **ENSO status:** NOAA Climate Prediction Center. **Ports:** NGA World Port Index (public domain). **Satellite imagery:** Esri World Imagery, under its terms.

**Your contributions** (place confirmations, corrections and notes sent to the editor) are licensed by you under CC BY 4.0, with a licence to the app's company to combine them with the ODbL data above (Terms, section "Contributions").

The official warnings come from the regional centres (RSMC Nadi, Météo-France Polynésie, NHC, PTWC and the others named on each row); this app repeats and links them and is never their substitute.