A vector grid in 2 x 2 km resolution showing the environmental sensitivity and the underlying themes that have caused the final vulnerability in spring for the Baltic Sea area. This dataset has been produced by COWI ( http://www.cowi.dk) for the BRISK project (Sub-regional risk of spill of oil and hazardous substances in the Baltic Sea, http://www.brisk.helcom.fi/). Sensitivity map is based on datasets provided by the BRISK Project Partner organisations. The detailed documentation of what partner provided what data is given in the Annex of the document: 70618-3.1.2.2 Data Collection Report. Field explanations: RS_SR: Rocky shores and stony reefs, Estuaries; Estuaries, Lagoons: Coastal lagoons, Bays: Shallow inlets and bays, Sandbanks: Underwater Sand banks, Beach: Sandy beaches, Seagrass: Sea grass, meadows, Spawning: Spawning area for fish with demersal eggs, Nursery: Nursery areas for fish on shallow water, Off_spawn: Offshore spawning areas for fish with pelagic eggs, Win_Birds: Wintering areas for sea and shore birds, Staging: Staging areas for migrating sea and shore birds, Breeding: Breeding areas for sea and shore birds, Moulting: Moulting areas for sea birds, Mammals: Marine Mammals, Protected: Protected areas, Aquacult:: Fish farms and aqua cultures, Sum: Weighted vulnerability index, Index: Not used Weighted vulnerability index is used to depict vulnerability for the Baltic Sea. Certain parameters have been used to map the environmental sensitivity to oil and each has been weighted for four seasons based on expert judgment. Two alternative sensitivity weighting matrices were also prepared in order to evaluate and validate the results. The sensitivity maps has been combined with the data on oil impact to model environmental damage, and to quantitatively compare the relative efect of the proposed new measures to reduce the risk, impact and damage of oil. Underlaying paramenters used in the vulnerability calculation can be obtained from HELCOM map service under Shipping\Risk Assessment (BRISK)\Environmental parameters -folder.