Oil spills are a disaster for the ecosystems and could affect easily the economy, e.g. fishery and tourism. The large catastrophic events which was caused by accidents on oil platforms (Deep Water Horizon) or by large ship accidents (e.g. Exxon Valdez) are very well known. But there are many oil contaminations which are not recognized by the general public. Partly also caused by accidents and failures on ships and oil platforms, but also origined in illegal oil dumping into the sea. Copernicus data, especially the data of Sentinel-1 helps to detect such oil spills and can observe the spread of the oil. This helps on the one hand to react and plan to minimize the contamination and on the other hand it gives the possibility to find the polluter in the case of illegal oil dumping.