Immersive Space to Think (IST) builds on our prior work on "space to think" and "semantic interaction" with large 2D displays for sensemaking. IST is a novel type of immersive analytics that leverages two key aspects of immersive virtual reality (VR) and augmented reality (AR) technologies to support analytic synthesis. First, immersive technologies can provide nearly unlimited 3D space that allows analysts to use space in more expressive and nuanced ways to organize data.