The paper presents the results of works related to the analysis of microclimate hazards in the Crystal Caves of the Wieliczka Salt Mine. The paper focused on the development of a device for monitoring, testing and preliminary measurements of the gravimetric water content of rock in the Crystal Caves. The multisensory measurement system equipped with capacitive soil moisture sensors has been developed, calibrated and optimised. The system was used for monitoring moisture content in the sidewall and thill of the Crystal Caves.