More than 1,000 hidden coral reefs have been mapped across northern Australia after scientists combined hundreds of satellite images

Thousands of kilometres of northern Australia's coastline can look deceptively simple from above. Much of the water is clouded by sediment, making coral formations difficult to distinguish from the shifting patterns on the surface. According to the Australian Institute of Marine Science (AIMS), in 2026, scientists found a way to make those hidden structures easier to see without sending a survey vessel into the water. By combining large numbers of satellite images, researchers from the Australian Institute of Marine Science and the University of Queensland identified and mapped more than 1,000 coral reefs that had not previously appeared on detailed maps. The work stretches from Western Australia towards western Cape York in Queensland, giving marine planners a much clearer picture of reefs that had remained largely unmapped.How one researcher turned changing satellite images into a reef-mapping toolAs reported by AIMS , the idea behind the project began years before the new maps were produced. Dr Eric Lawrey, an e-Atlas project manager at the Australian Institute of Marine Science, had been looking at satellite imagery of Australia's northern coastline when he started noticing shapes that appeared to be reefs. There was a problem, though. A single image rarely gave a reliable view.Northern Australian waters can be heavily affected by suspended sediment, leaving the sea looking almost uniformly coloured from above. Reefs beneath the surface were difficult to separate from the constantly moving patterns created by the water. Lawrey realised that the movement itself could help solve the problem.Hundreds of images revealed what one could hideRather than relying on an individual satellite photograph, the team combined roughly 200 images of the same areas, taken at different times. The changing water patterns moved from image to image. The reefs did not. When the images were combined, those shifting surface effects became less prominent while the persistent shapes of reefs were strengthened. Structures that had been difficult to distinguish in individual photographs became much easier to recognise.It was a form of desktop exploration. There was no need for the researchers to travel by boat simply to establish where many of these formations were located. Once the reefs could be seen more clearly, their boundaries could be mapped.More than 1,000 reefs emerged from the imageryAccording to AIMS official X (Twitter) post, the mapping revealed more than 1,000 previously uncharted coral reefs across northern Australia.The source describes the area as extending from the Houtman Abrolhos in Western Australia to western Cape York in Queensland. Many of the reefs are considerably smaller than those associated with the Great Barrier Reef, but their combined presence changed the picture of how extensively coral habitat is distributed along the northern coastline.The team ultimately produced a much broader classification of the region, identifying more than 3,600 coral reefs alongside about 2,900 rocky reefs.Why mapping the newly visible reefs was harder than expectedThe technology made the reefs visible, but it did not turn the entire process into an automatic exercise. Early attempts to use automated methods produced too many false positives. The team therefore relied heavily on manual interpretation.Reportedly, it took around 700 hours to digitise the reefs and assign classifications to them. That work also required different approaches in different parts of the coastline. The formations were not all shaped in the same way, and local geology and tidal conditions affected what appeared in the imagery. The Kimberley was particularly demanding. Tidal ranges there can reach about 12 metres, producing reef structures that look very different from those found elsewhere.Some reefs had unusual structuresThe mapping exercise was not simply a matter of finding patches of coral and drawing lines around them. Some reefs occur high in the intertidal zone, with algal ridges surrounding them. Others form structures with shallow lagoons and walls that allow coral to grow vertically. The team also encountered ancient shoreline rocky reefs, fringing coral reefs, oceanic banks and sand banks while building a more detailed picture of the northern Australian seascape. This variation meant the researchers had to understand the physical character of each region before deciding how best to interpret the satellite imagery.Northern Australia had been poorly mappedMarine charts had provided some information before this project, but they were designed primarily for navigation. Their purpose was to alert vessels to hazards rather than produce a detailed ecological inventory. Coral reefs and rocky reefs were not necessarily separated in the way a marine habitat map would require. As a result, large sections of the northern coastline had remained comparatively poorly surveyed from an ecological mapping perspective.The maps could change how marine areas are managedKnowing where habitats are located matters for the people responsible for managing coastal waters. The new datasets give marine planners, Traditional Owners and other managers more detailed information about the distribution of reefs. That can be particularly useful in areas where previous mapping provided only a broad indication of underwater hazards or habitat.The researchers applied the imagery approach to the Great Barrier Reef, where it was used alongside a separate University of Queensland effort to remap outer reefs. That work identified hundreds of additional reefs and helped remove formations that had previously been incorrectly identified as reefs. The revised Great Barrier Reef dataset was under review by the Great Barrier Reef Marine Park Authority at the time of the AIMS announcement, as reported by AIMS official website.You use AI every day. Now get your AI Quotient. Take the AIQ test.