An atoll as large as a district in Paris, Mururoa in French Polynesia, has remained isolated and inaccessible for nearly thirty years since the last French nuclear test, named Xouthos, on January 27, 1996. The atoll was used for nuclear testing between 1966 and 1996, and since the end of the testing program, it has not been opened to civilians, tourists, or economic activity. During this time, France conducted 193 nuclear tests on Mururoa and Fangataufa, including 46 aerial tests and 147 underground tests in shafts that were 600 to 1000 meters deep. The 193 galleries dug into the coral still contain hundreds of tons of radioactive waste and contaminated materials, which have not been removed. The first French nuclear test in Polynesia took place on July 2, 1966. Between that date and the Xouthos test in January 1996, France conducted 193 nuclear tests, 167 directly on Mururoa and the rest on Fangataufa. Among them, 46 tests were carried out in the open atmosphere between 1966 and 1974, before international pressure forced a shift in method. Starting in 1975, and continuing until the end of the tests in 1996, 147 underground tests took over. The technique involved drilling shafts 600 to 1000 meters in depth, first under the coral crown of the atoll and later directly under the lagoon due to a lack of space. In these shafts, nuclear charges were lowered before being triggered, a practice intended to limit the fallout to the open air. However, nature sometimes reminded the limits of this method: in March 1981, the Defense Minister Charles Hernu had to admit before the National Assembly that a cyclone had dispersed debris from a nuclear explosion on the atoll, creating what he described as a new radiological situation. After the tests were completed, France began dismantling the surface infrastructure on the Mururoa and Fangataufa sites. Buildings, military installations, and visible equipment gradually disappeared from the landscape. However, underground, the 193 galleries and shafts dug into the coral have never been emptied of their contents. According to a recent parliamentary report, hundreds of tons of radioactive waste and contaminated materials still rest inside these galleries, buried within the very body of the atoll. Plutonium and other radionuclides may have even been dispersed over thousands of kilometers following certain atmospheric tests. However, an investigation conducted by the International Atomic Energy Agency between 1996 and 1998 concluded that no corrective measures were necessary on the sites, neither in the immediate nor for the future, from the point of view of radiological protection. This finding has not prevented France from continuing, out of precaution, to permanently monitor the level of radioactivity in the atoll's environment. The local populations, exposed to the fallout from the atmospheric tests in the early years, have indeed obtained a form of official recognition with the creation, in 2010, of the Committee for the Compensation of Victims of Nuclear Tests, tasked with handling the cases of people who fell ill due to these experiments. The atoll, however, continues to live in isolation, between discreet monitoring and total absence of civilian access. A French territory that is not visited, that is rarely flown over, and that keeps, under its tranquil surface, the buried memory of a nuclear program whose exact consequences remain, in many ways, incompletely measured.