Rivière souterraine du Heurt, Underground cave system in Senneville-sur-Fécamp, France.
Rivière souterraine du Heurt is a natural cave system with water-filled passages beneath the limestone cliffs of the Seine-Maritime coastline. The network was carved by erosion through calcium deposits and continues to be shaped by flowing water.
The cave system took shape during the Quaternary period through erosion of limestone deposits. This geological process carved the underground passages that exist today.
Local stories connect this place to the maritime traditions of the coastal village. The underground river holds a special place in how residents understand their connection to the sea.
Access depends on water levels and seasonal conditions, so contact local authorities before visiting. Planning ahead ensures you can explore safely and appropriately.
Where freshwater meets the influence of the English Channel, distinctive limestone formations develop underground. This rare mixing zone creates geological structures that form in few other places.
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