The ability to interactively visualize the complex products of three-dimensional simulations is a key aspect in the validation and verification process of numerical algorithms and frameworks. Computational astrophysics, which benefits from the rapidly increasing computing resources offered by the use of massively parallel mainframes, is a challenging playground to scientific visualization. In this paper, we describe a graphical package developed in the framework of IDL Object Graphics. The requirements governing its design are defined in the context of the COAST software project which aims at providing an ensemble of enabling tools and techniques for the development and the validation of major simulation codes. This covers a wide range of applications, including cosmological formation of large-scale structures, turbulences in the interstellar medium, stellar magnetohydrodynamics, and formation of proto-planetary systems. The use of IDL Object Graphics provides an interactive and immersive visualization of complex scenes where various fields of different nature are entangled. Three-dimensional scalar and vector fields distributed over regular mesh grids or more complex structures such as Adaptive Mesh Refinement data, as well as N-body systems, can be visualized in a number of different, complementary ways.