The purpose of this study is to determine the risky areas by simulating trajectory of ship based oil spill in Bay of Izmir. To get well informed about fate, this study makes the best possible use one trajectory model. PISCES 2 (Potential Incident Simulation, Control and. Evaluation System), has been conducted for simulation of main weathering processes of oil spill. Hence in order to identify the risky areas, two scenarios have been developed depending on the type and amount of pollutants. In this study it is concluded that Yenikale, Inciralti and Guzelbahce will be at risk of contamination in case of accidental oil spill at Yenikale Entrance. Finally, the PISCES 2 software provided highly reliable solutions in evaporation rate and dispersion rate calculations when compared to approaches accepted in the literature. However in the surface area calculations, there is a serious difference between the size of the area calculated by the software and the size of the area proposed by oil spill science.