Visualization has been an integral part of environmental simulation to facilitate comprehension of complex environmental processes. Traditionally, data analysis and visualization are often considered and performed as post-processing steps after a simulation has been run. Despite the advantage of these approaches, any user interaction with the model computation is often not allowed. This paper introduces an alternative approach to exploring an environmental model, TOPMODEL, where the model-supported simulation process can be visualized, controlled and tuned through interactive steering in a 3D virtual environment. This virtual environment can run on a WEB browser and is developed using the component software technology, which allows users to assemble modeling and visualization components with flexibility. The 3D visualization of the model is accomplished by Java/VRML interaction through the External Authoring Interface (EAI). The interaction through process steering enables users to experiment with model computation and observe the model behavior through dynamic 3D graphics, thereby enhancing investigation of the dynamic environmental process. The performance of the Java/VRML approach has also been examined through the comparison with the Java 3D and the conventional 2D approaches.