This dataset contains beached oil concentrations along the Mediterranean coastline, derived from an ensemble of oil spill simulations spaning 5 years (2018-2022) and using the MEDSLIK-II numerical model (https://www.medslik-ii.org/). The study modeled an operational oil spill scenario (22 API oil released at a rate of 0.17 tons/hour for 120 hours per spill ) featuring 203 release locations uniformly distributed between 10 and 50 km from the Mediterranean coast and activations every 5 days. For each individual point-source release, a beaching event is defined by the volume of oil that reaches a specific 150-meter coastal segment and remains fixed there until the end of the simulation. This value is expressed as a concentration in tons/km and recorded at the final simulation time step. The dataset includes a single coordinate called event, which serves as a unified index for all beaching events merged across the entire simulation ensemble. Consequently, the events are ordered sequentially: the first set of indices corresponds to Simulation 1, followed by the events from Simulation 2, and so on. All events are characterized by the following variables: release_lat: Latitude of the oil spill release location that originated the event. release_lon: Longitude of the oil spill release location that originated the event. release_date: Date of the oil spill release that originated the event. latitude: Latitude of the midpoint of the coastal segment where the beaching event occurred. longitude: Longitude of the midpoint of the coastal segment where the beaching event occurred. beached_conc: Oil concentration of the beaching event (expressed in tons/km). country: The country to which the coastal segment belongs. The analysis exclusively considered 18 Mediterranean countries: Albania, Algeria, Croatia, Cyprus, Egypt, France, Greece, Israel, Italy, Lebanon, Libya, Malta, Montenegro, Morocco, Spain, Syria, Tunisia, and Türkiye. Coastal segments belonging to any other country are labeled as 'None'.