Copernicus Sentinel data is being used to monitor illegal, unreported, and unregulated fishing (IUU) in UK Overseas Territories. IUU is a huge threat to marine ecosystems and is undermining efforts to conserve and manage fish stocks. A common tactic when it comes to flouting maritime laws and engaging in such illegal activities at sea involves illicit vessels switching off their automatic identification system (AIS), vessel monitoring system (VMS) or any other systems through which they can be identified. However, Sentinel data can still be used to detect vessels that are trying to evade the authorities, thereby contributing to the protection of marine resources and ecosystems.