As training systems are often designed for procedural task learning, we propose an adaptive training system (OSE) in this context to explore how informed interaction supported by a decision making module (GULLIVER) contributes to adaptive knowledge acquisition in a virtual environment. Visualization metaphors and audio messages are displayed as feedback to guide the learner, which is essential to this training. First results show that our system provides an adaptive guiding which is efficient for beginners. Though we focus on fluvial navigation training, the results may be relevant to other applications.