To test passive seismic interferometry (PSI) in underground mining environments, we carried out an active-source seismic and continuous noise measurement in a mine gallery of a former radioactive waste repository - the Asse II salt mine (Lower Saxony, Germany). To analyze the active-source data, we process the data inspired by conventional seismic processing techniques. On the contrary, for the passive-source data, we first perform an illumination diagnosis to identify and separate seismic wave types. Subsequently, we apply PSI by cross-correlation for the retrieval of body-wave arrivals and finally apply selective-stacking. In this context, we refine processing procedures for PSI inside of mine galleries and point out that data recordings of <24 h and summation times of 10 min to 30 min during selective stacking are sufficient when applying PSI to underground noise data. Using PSI imaging results, we identify several pre-known and unknown geological structures exceeding the number and distance of structures determined from active-source imaging results. Here, PSI showed advantages over the active-source seismic data regarding resolution, energy distribution, and spatial extent.