The analysis of the ship layout from the point of view of safe and orderly evacuation represents an important step in ship design, which can be carried out through agent-based evacuation simulation tools, typically run in batch mode. Introducing the possibility for humans to interactively participate in a simulated evacuation process together with computer-controlled agents can open a series of interesting possibilities for design, research and development. To this aim, this article presents the development of a validated agent-based evacuation simulation tool which allows real-time human participation through immersive virtual reality. The main characteristics of the underlying social-force-based modelling technique are described. The tool is verified and validated by making reference to International Maritime Organization test cases, experimental data and FDS + Evac simulations. The first approach for supporting real-time human participation is then presented. An initial experiment embedding immersive virtual reality human participation is described, together with outcomes regarding comparisons between human-controlled avatars and computer-controlled agents. Results from this initial testing are encouraging in pursuing the use of virtual reality as a tool to obtain information on human behaviour during evacuation.