This study attempts to investigate the sense of presence in a fully immersive virtual environment. The methodology applied in this study used protocol analysis for data collection. A preliminary experiment was conducted to explore noticeable phenomena to develop a hypothesis for the final experiments. Four different virtual reality models, representing four different kinds of virtual space, were navigated in C6 (CAVE facilities) by two human subjects. Results of the research in this direction have provided valuable understanding regarding the sense of presence in the virtual environment.