Open datasets for maritime domain awareness: a practical catalog

You can build a real maritime domain awareness (MDA) picture without buying a single feed. We did — live.marineaware.com runs on nothing but the datasets below. This guide is the practical catalog: what each open dataset is, how to reach it, what it is genuinely good for, and where it runs out. For the terms used here, see the MDA glossary; for how to turn these feeds into findings, see the maritime OSINT guide.

How to read this catalog

MDA is a fusion problem: no single feed answers a real question. Group the open datasets by the role they play, and the picture assembles itself:

• Cooperative tracking — where vessels say they are (AIS).
• Non-cooperative imagery — where they actually are (SAR, optical).
• Environment — why they behave as they do (metocean, bathymetry).
• Activity & context — fishing, thermal, trade, identity, emissions.

Cooperative tracking: open AIS

AIS is the backbone — VHF broadcasts of a vessel’s identity and position — but the open versions are sampled, not exhaustive.

• AISStream.io — a free, live WebSocket of AIS position reports, filterable by bounding box. Best for: a live snapshot of who is in a zone right now. Limits: the free tier throttles hard across many areas at once.
• Global Fishing Watch (GFW) — open AIS-derived events (gaps, loitering, encounters) and satellite vessel detections, with APIs and bulk download under a CC BY-SA licence. Best for: pre-computed behavioural signals without building your own pipeline.
• NOAA MarineCadastre.gov — free bulk historical US coastal AIS. Best for: training and backtesting on clean archives.

The catch, quantified: a 2024 Nature study found roughly 75% of industrial fishing vessel activity absent from public AIS. Open AIS tells you about cooperative vessels; the interesting ones are often silent — which is why you need imagery.

Non-cooperative imagery: Copernicus Sentinel

The European Copernicus programme publishes two open datasets that are the heart of open dark-vessel work, both free via the Copernicus Data Space Ecosystem (STAC catalog, OData, S3).

• Sentinel-1 (C-band SAR) — radar that sees hulls in any weather, day or night, at ~5–20 m. This is the open dataset for dark-ship detection: cross-reference radar detections against AIS, and a hull with no transponder is a candidate. Limits: 6-day-class revisit and metre-scale-to-tens resolution — it samples a chokepoint, it does not stare.
• Sentinel-2 (optical, multispectral) — 10 m visible/near-infrared, 5-day revisit. Best for: daylight confirmation and coastal/port context. Limits: cloud cover, and no imaging at night.

For a zero-setup daily image, NASA GIBS / Worldview serves pre-rendered global true-color snapshots (MODIS/VIIRS) with no key — coarse (250 m class) but instantly usable as context.

Environment: metocean and bathymetry

Behaviour without weather is ambiguous — a loitering vessel may simply be holding station in heavy seas. Open metocean resolves it.

• Copernicus Marine (CMEMS) — currents, sea-surface temperature, salinity, sea level, waves; global to regional, hindcast to forecast. Open via Toolbox API and NetCDF.
• NOAA GFS / WaveWatch III / RTOFS — global wind, wave and current forecasts, open via NOMADS/GRIB.
• Open-Meteo — a free, no-key REST API for wind, gusts, wave and swell height at a point; the fastest way to add a transit-condition read (this is what the live dashboard uses).
• GEBCO_2024 / EMODnet Bathymetry — open depth grids for under-keel clearance and routing bounds.

Activity & context

• NASA FIRMS — near-real-time thermal anomalies (fires, gas flares, hot spots); a useful activity proxy near ports and industrial coasts. Free key.
• Global Fishing Watch fishing effort — open, gridded AIS-derived fishing effort, 2012 onward; the backbone of open IUU-fishing analysis.
• UN Comtrade — open bilateral commodity trade flows for demand and floating-storage context (free key, generous limits).
• Equasis — a free-registration vessel registry: identity, ownership, Port State Control and ISM records for due diligence and identity resolution.
• EU MRV / THETIS-MRV — open, ship-level verified CO₂ and fuel data for ships calling the EU/EEA; the calibration anchor for open emissions estimation and the context behind CII, EU ETS and FuelEU.

A minimal open MDA stack

If you want the shortest path to a working picture, this is the stack behind our demonstrator:

1. AISStream.io for live positions in your areas of interest.
2. Global Fishing Watch for derived gap/loitering/encounter events and SAR detections.
3. Copernicus Sentinel-1 for dark-ship cross-checking; Sentinel-2 / GIBS for optical context.
4. Open-Meteo for metocean.
5. NASA FIRMS for thermal activity.
6. Equasis / UN Comtrade for identity and trade context.

Fuse them, and you have MDA. The full source catalog — including the licensed options — is on our data & methods page.

Where the open stack ends

Open datasets are a genuine baseline, not a ceiling. Free AIS is rate-limited and cooperative; open SAR revisit is multi-day and resolution coarse; licences vary (Sentinel and NASA are permissive; GFW is CC BY-SA; always check before redistributing). The moment you need persistent monitoring — a vessel count that is a count, an AIS gap that is a real gap, a dark ship you can re-observe within hours — you are into licensed satellite AIS (Kpler, Spire) and high-revisit commercial SAR (ICEYE, Umbra, Capella). How that transition works, and what fine-tuned models add on top, is covered in from open source to operational.

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See these datasets fused and scored, live, at live.marineaware.com. To build the operational version on your own areas of interest, talk to us.