3 km from the campsite, located between Vaux Moretz and Chongnes. The groin is a river but here at its source it is a chasm that may seem quiet but in times of flood the flow of the esu is incredible. It is fed by groundwater.
This place is very appreciated by cavers because of its length, only the first 2100 meters have been explored, this Vauclusian resurgence (because it is vertical) has most of the time a zero flow from spring to autumn, and can suddenly see the flow changing due to a storm.
Its name comes from the noise the river makes when it leaves the resurgence, the water can rise very quickly.
More information: https: //bugeysud-tourisme.fr/noesit/!/fiche/source-du-groin-118167/