The main objective of this research is developing a simulation tool that provides information of detailed ship behavior in a specific navigational environment, on both the ship traffic level and the individual ship level, for safety analysis, decision making, planning of ports and waterways, and design of mitigation measures. In this research, we have developed the Artificial Nautical Traffic System (ANTS) model for maritime safety. The simulation method proposed is able to provide realistic ship traffic behavior by using the agent based model and the artificial force field. The ODD protocol (Overview, Design concepts, Details) has been a great support for detailed description of its methodology, concept, structure, calibration, and validation. Ship AIS data is treated as real world data, therefore the data have been analyzed and utilized. A Dutch case and a Chinese case have been studied to demonstrate model implementation, calibration, validation, and the applications.