Abstract: This paper describes our research in full-surround, multimodal, multi-user, immersive instrument design in a large VR instrument. The three-story instrument, designed for large-scale, multimodal representation of complex and potentially high-dimensional information, specifically focuses on multi-user participation by facilitating interdisciplinary teams of co-located researchers in exploring complex information through interactive visual and aural displays in a full-surround, immersive environment. We recently achieved several milestones in the instrument's design that improves multi-user participation when exploring complex data representations and scientific simulations. These milestones include affordances for "ensemble-style" interaction allowing groups of participants to see, hear, and explore data as a team using our multi-user tracking and interaction systems; separate visual display modes for rectangular legacy content and for seamless surround-view stereoscopic projection using 4 high-resolution, high-lumen projectors with hardware warping and blending integrated with 22 small-footprint projectors placed above and below the instrument's walkway; and a 3D spatial audio system enabling a variety of sound spatialization techniques. These facilities can be accessed and controlled by a multimodal framework for authoring applications integrating visual, audio, and interactive elements. We report on the achieved instrument design.