Located in the Famenne-Ardenne UNESCO Global Geopark, the Han-sur-Lesse cave is a major touristic attraction of Wallonia. The cave is a double shallow-hole—resurgence system developed in the Givetian limestones. When the cave is flooded some sections become inaccessible for the touristic activities. During floods, upstream some narrow sections or sumps, water level can rise up to 9 m creating unusual hydraulic pressure that could destabilise screes on which touristic footpaths are constructed. To quantify these processes, water level probes were installed and topographic nails were fixed on different cave roofs or walls and blocks. Thirteen water level probes were installed inside the cave. The water table monitoring allows to have a better understanding of the underground flow dynamics. Established correlation between river discharge and the groundwater level inside the cave will allow a better management of the touristic activities. All probes react in a similar way and show an important hysteresis process between the flooding and receding periods in the relation “discharge versus water level”. This is due to the high hydraulic conductivity and porosity of the karstic aquifer as it was previously detected by tracer tests. An instrumentation was also implemented to quantify block movements in the cave. Measurements are monthly conducted with portable devices at fixed stations located in the cave at specific spots: strata, rock blocks, paths, etc. Three methods are used; they consist of measuring (1) variations in slope, (2) variations in length between two points and (3) scanning of reflector positions using a laser theodolite. During this long-term monitoring, every change of parameters (water levels, tilts, distances, etc.) must be interpreted in terms of potential modifications of the karst system requiring detailed investigations.