Synthetic Aperture Radar (SAR) images have been extensively used for the detection of oil spills in the marine environment as they are independent of local weather conditions, cloudiness and sun illumination. The objective of the study was to provide the users with specific knowledge on SAR image availability over a target area and assess the monitoring capability (visibility of an area) with respect to the requirements for oil‐spill detection and marine environment protection over the south‐eastern part of the Mediterranean Sea. For this purpose, a web GIS tool has been implemented, enabling the users to submit their queries and receive answers in the form of reports and statistics, concerning the current image acquisition capability over the area of interest. It also provides the user with graphic representations of the sensors' swath coverages over the same geographic location. The system has been tested over the Hellenic Seas and the resulting figures denoting the temporal resolution in the observation are analysed and discussed. The analysis shows that the operation of the Envisat satellite, in conjunction with ERS‐2 and Radarsat satellites, has significantly improved the monitoring capability. As shown, the increase in the number of observations over a target location can reach theoretically a level of 130%. In conclusion, the study provides the user with an assessment of the remaining technological gaps and unmet user needs in the domain of marine environment protection.