DARK ships are vessels that have switched off their AIS transponder, while the shadow fleet comprises ships owned through shell companies and flagged in jurisdictions with minimal oversight, making ownership hard to trace; the two categories often overlap, with shadow fleet tankers sometimes going dark during transfers.
AIS is vulnerable because it was designed for collision avoidance, not surveillance, meaning ships can broadcast false positions or names, or simply toggle off the transponder, and analysts may cross-check AIS with satellite imagery to spot inconsistencies, such as a vessel moored in Bandar Imam Khomeini when AIS shows movement south of Oman; satellites can also help verify streaks of activity during gaps.
The core toolkit includes MarineTraffic and VesselFinder for AIS data, Equasis for ownership information, TankerTrackers for satellite tracking, and sanctions checks through OFAC lists, with Shodan useful for identifying exposed onboard systems.
Extended OSINT tools add satellite imagery, corporate research, and geospatial analysis, including Global Fishing Watch, Sentinel Hub, OpenCorporates, and OpenSanctions, while the article emphasises careful, stepwise investigation from initial detection to sanctions screening and final assessment. According to NASA, imagery can support interpretation of large-scale fleet movements, though it may not confirm vessel identity with certainty.