We study groundwater flow and transport mechanisms on multiple scales, especially heat transport, coupled mechanical deformation and environmental impacts. This is motivated by the thrill of exploring the enormous diversity of the geo-environment hidden beneath our feet from the depth of a few centimeters to kilometers. Our work seeks to expand our understanding of fluctuations in the subsurface as a consequence of urbanization, geothermal energy use and climate change. To achieve this, we link multiple disciplines such as hydrogeology, geophysics, rock mechanics, computational, energy and environmental science. Among our means are new field, laboratory and model-based investigation techniques. The focus of our research is also reflected in our leading role in undergraduate and graduate teaching of around 20 different courses at the institute.