A GIS-based environmental atlas is suited as an operative tool for oil and chemical accidents at sea and for areal planning. Simulations of accidents and mapping of risks can be made. Identifying sensitive resources and developing protection strategies will be easier. The environmental atlas is used by ArcView GIS software, with which it is possible to visualize, explore, query, and analyze the data. The atlas includes information on shorelines, infrastructure, sensitive biological resources, and human-use resources. Textual and tabular information such as protected areas and contact information of local experts is linked to the maps. The application allows rapid evaluation of changing scenarios and circumstances. Data from oil spill trajectory models, remotely sensed data, and satellite images can be imported to the application.