Water body movements in bays and seas should also be determined for the solution of many engineering problems. This study aims to determine the hydrodynamic characteristics of the movements of the water body in Ayvalik Bay, one of the most important touristic coastal zones of Turkey with a great number of islands. Ayvalik Bay is located in the Ayvalik county of the province of Balikesir in the northern part of the Aegean Sea in Turkey. For this aim site measurements and numerical model studies have been carried out. In order to determine the hydrodynamic characteristics of Ayvalik Bay, AQUASEA model was used. Model verification and various scenarios tests were carried out. The output of this project will be basis of pollution studies in Ayvalik Bay. The effects of landfill road (between Ayvalik and Dolap Island) on water circulation could be seen and necessary suggestions were presented. The results of this study would be an important input in the contamination prevention efforts for the sustainable use of the Ayvalik Bay. Knowledge about the interaction between the water body movements and the environmental conditions is crucial for future planning and solution of engineering problems.