To determine the safety levels in a certain sea or port area, one can use the more traditional risk or safety assessment models, which determine the shipping risk in an area based on 'static' traffic and accident statistics. The introduction of AIS has provided possibilities for new assessment methods. This paper describes the development of a dynamic real-time risk index. The risk index determines the risk (or safety) level of a ship given the movements of actual traffic and the environmental conditions surrounding a ship, based on AIS. The paper also describes how this index could be used in real-time dynamic risk assessment and in operational environments, but also how it can be used to study the development of risk levels in certain areas over larger periods of time.