Tourists often travel to experience the natural beauty of a destination such as the Great Barrier Reef (GBR) in Australia. This nature-based destination attracts millions of tourists every year because of its outstanding underwater aesthetics. Recently, parts of the GBR have been degraded by warming sea temperatures and other local anthropogenic influences, threatening the Reef aesthetics and tourism in the region. In order to deal with this topical issue, the current research investigates tourists’ aesthetic assessment of environmental changes in the GBR ecosystem. Research outcomes indicate that tourists’ perceived beauty of the Reef is sensitive to environmental changes. The disappearance of sea animals (colourful fish, turtle), degrading coral and decreasing water quality negatively influence their aesthetic assessment, which can reduce tourist visitation in the long-term. Hence, sustainable tourism development in the GBR regions can only be achieved when government support for environmental management is strengthened. Conservation programs of the GBR should expand beyond coral restoration for controlling water quality, reducing pollution and protecting aesthetically appealing sea animals.