The Neptune’s Caves
The Neptune’s Caves, formerly “Grottes de l’Adugeoir” located in Petigny – Couvin, were dug into the limestones of the Middle and Upper Devonian. It is the intersection of a meander of the Eau Noire which, descending from the sandstone Ardennes, intersects, 100 m lower, the limestone and shale banks of the Fagne-Famenne depression.
The Caves of Neptune open on the left bank of the Eau Noire. These are active caves, since an arm of the river rushes into them and emerges almost three km further, at the Pont d’Avignon cave, in Nismes.
The rock made up of a set of layers of fossilized corals from the “Brachipodes” family is home to numerous galleries.
They were discovered at the end of the 19th century and consist of two floors, lower and upper, today connected by an artificial gallery.
Only 10% of the underground route of Eau Noire is known. Explorations are still ongoing.
Nestled in the heart of Calestienne, the Grottes de Neptune site welcomes you to a unique and preserved nature!
Explore the caves to discover an underground world housed in the depths of a rock hundreds of millions of years old, or let yourself be guided on our trails in search of species typical of this corner of nature classified Natura 2000.
A journey several meters underground!
Nestled in the heart of Calestienne, the Grottes de Neptune site welcomes you to a unique and preserved nature!
Explore the caves to discover an underground world housed in the depths of a rock hundreds of millions of years old, or let yourself be guided on our trails in search of species typical of this corner of nature classified Natura 2000.
The Underworld
The underground environment offers landscapes of great beauty, sometimes breathtaking, of rich diversity, but also very vulnerable.
Some of the most interesting discoveries result from explorers willing to squeeze through narrow cavities and brave turbulent underground waters.
Speleologists speak of the conquest of karst. They can dig for weeks to access new galleries.
At the Neptune’s caves, known as the Grottes de l’Adugeoir, they have the secret hope of accessing the siphon which would allow them to reach the resurgence of the Eau Noire located in Nismes.