ABSTRACT The geographic information system (GIS) is an objective and standardized oil spill impact assessment tool. In addition to the impact assessment, the GIS provides a helpful tool for judging the size of the impact, choosing environmentally sound cleanup techniques, and planning resources utilization. All information put into a GIS, including daily activity reports, will constitute the essential base for claims from the International Oil Pollution Compensation Fund (IOPC Fund). Impact assessment. Before cleanup activities start, an impact assessment is made. The impacted area is geographically defined in the field with the detailed geographic position system (dGPS) and maps. Type of coastline, spill volume, and type of oil are documented for each impacted area. If necessary, photos and other information concerning the impacted area are included in the GIS. Determination of cleanup method. Documented information from the impact assessment is analyzed together with databases containing ecological sensitivity maps, cleanup methods, and experience. The analysis made using the GIS will suggest what cleanup method/s should be used and how best to use resources. The cleanup method(s) chosen by use of the GIS is presented in digital maps and tables of resources needed. Daily activity reports. All daily activities are documented in the GIS. These include time spent, costs, site, amount of oil cleaned up and method used for cleanup, transfer of oil, and waste disposal. Total and specific cost for each impacted area is calculated daily. Commanders report. The GIS provides the commander with a total report of all actions taken during the cleanup operation. The report contains total costs, claims, experience, geographical location, date and time, and an impact assessment. Advantages of the GIS. The GIS provides a standardized and objective impact assessment for each contaminated area and at the same time suggests what cleanup method to use. The system can present daily reports of information and activities undertaken, and easily specify the cost for each activity. The GIS also can present a final report immediately upon completion of the work.