Around the world, thousands of reservoir dams have flooded valleys and become concrete symbols of the Anthropocene. These landscapes, as well as material or immaterial cultural heritages, were flooded and thus became invisible, even though they remain in the memories of local populations. Today, alternative technologies can enable inhabitants to reappropriate these lost heritages and, in a way, make them visible again. 3D digital tools can effectively recreate representations of these landscapes and restore the visibility of these underwater heritage sites. In this study, we propose a 3D geographic information system methodology combined with 3D geovisualization to recreate sunken landscapes, and we demonstrate the results using the valley of the Gorges de la Loire in France as an example. We show how developing a historical database can provide a "backup copy" of lost landscapes and cultural heritage sites, enabling populations to safeguard and restore these features in their memory following flooding.