For many years, the Great Barrier Reef (GBR) in Australia has been under serious threat of rapid decline due to a number of factors including heat stress events and the crown-of-thorn sea star. Human behaviour can directly and indirectly contribute to these factors, for example, through increased water and carbon footprints. In this paper, we illustrate the potential benefit of a large-scale mixed reality visualisation methodology in communicating complex GBR data, including exploring the impact of individual factors on the coral reef ecosystem. We present an immersive interactive visualisation, combining tiled displays (PerceptuWall) and head-mounted displays (Oculus DK2, Google Cardboard), that dynamically presents individualised coral damage information based on viewers' footprint inputs. The immersive tour provides a use-case for promoting understanding of how human behaviour impacts on GBR health by linking individual or regional actions to global outcomes, with the additional advantage of capturing the public's attention for immersive technologies.