A long time ago, Humanity had a close relationship with the underground environment that provided shelter. However, it has since abandoned it and colonized a planet on which it now has a preponderant action: the environmental changes that we impose on our environment have an action on the climate, on biodiversity and in return on ourselves. This is all truer for the underground environment in Europe, where the major cities of the Union stand side by side with the prehistoric caves that were once our homes. The water cycle, citizenship and sustainable development are well represented in the school curricula of European Union countries. These essential notions are closely linked to the underground environment, which is taught very little. We will work in an international team to produce and test teaching tools for teachers. These documents and case studies will be constructed in collaboration with specialists in the underground environment. They will be compatible with school curricula and will be disseminated to a wider audience. Through the European school community, our project aims to raise citizens' awareness and increase their knowledge of the importance of societal issues related to the underground environment.The underground environment is at the interface between the atmosphere, the lithosphere and the hydrosphere. Understanding the dynamics of the water mass flowing between these three compartments provides essential elements for understanding groundwater storage and flow velocity. Based on observations and measurements made directly in the field, we will build didactic models primarily for students but which we will also share on universitary and speleology networks. They will be used to provide information on the water resource : where does she come from, how is she managed, what is her economic importance, how can she be used sustainably and how fragile is she? Understanding the fast stream of groundwater and the state of imbibition of the rocks is critical to hazard assessment and understanding of flood risk. Due to the global warming, our citizen project will integrate the constraints of climate change for an enlightened understanding of the water resource management and an increasing flooding risk.The underground environment is also home to an incredible biodiversity. This subterranean life is both a treasure that must be preserved and an indicator of the state of preservation of the environment. Without the contribution of solar radiation, underground life forms are totally dependent on the production of biomass on the surface. Environmental management measures over cavities that support life are therefore essential. Some insectivorous animals that take shelter underground, such as bats, have an unknown role in agriculture and health. Safeguarding them is therefore also an important economic and social issue. We also want to make citizens aware of the need to consider the protection of this fragile environment, which is invisible to the public eye.Invisible from the public eyes, but not from cavers who regularly explore this environment with scientists. They are the witnesses and the key players in the management of this environment and will be our privileged partners in this project alongside academic researchers. They will lead students and teachers in the underground environment. Another strong point of our project will be to create links between cavers from different European countries, but also with researchers and the educational community. Some schools in the project have already had links with local scientific and caving networks. We are going to build on this experience to extend and develop it on the scale of a European cooperation.In the schools involved, pupils will start an incredible journey through space and time which continue an human underground adventure that began thousands of years ago. With the help of their teachers, scientists and speleologists, the students will start by becoming aware of the underground environment that surrounds them. Thanks to observation, measure and meetings, they will learn to understand it and then share this knowledge with their peers in other countries. These meetings will lead to the sharing of a common heritage and the discovery of a continuity of needs and issues.Each school will provide one case study per year. It will be published on the project twinspace, accompanied by data (measurements, maps, photographs, articles) and teaching tools to help teachers to use it. Once validated by partners, they will be proposed for publication and shared on educational, university and caving websites. Each one will be the subject of kakemonos, posters and videos. They will be used to raise public awareness of the underground environment and its link to our society. We present them in schools, during caving and geoscience congresses at the national and european scale.