Fontaine de Vaucluse is almost the sole outlet of an exceptional karst system, both in terms of the size of its drainage basin (1130 km2) and the thickness of the unsaturated (800 m on average) and saturated (>300 m) zones. The size of the system gives an approximation of the impact of lateral variability in ‘depositional environments’ of the carbonate facies, of processes of fracturing and karstification, and flow dynamics. The Messinian ‘structuring’ of this karst is typical of the Mediterranean region. The conduit that conveys water to the spring has been studied as far as the elevation of -204 below mean sea level and is the origin of the term vauclusian system, which defines a karst system in which the drainage network has developed below the level of the outlet. Upstream of the spring, in the the Sorgues region, rivers are associated with important societal issues (flood warning, irrigation, biodiversity, and green tourism).