Caves of Neptune (or of Adujoir)
The Green Guide

Useful information

Opening hours

guided tours (every 45min): Jul-Aug: 10.15am-4.45pm; rest of year: see Website


The River Eau Noire, so called because of black rock lining its bed, disappears into the Adugeoir chasm before resurfacing near Nismes. Visitors can see three tiers of galleries with fine concretions. The Eau Noire has not flowed through the upper gallery for centuries but floods the middle gallery when water levels rise. There are small boat rides along the underground river in the lower gallery which enable visitors to see a spectacular waterfall and a Son et Lumière show at the end of the trip.


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  • From €39 to €59
    MICHELIN 2021
    1.9 Km - rue de la Gare 10, 5660 Couvin
  • From €37 to €60
    MICHELIN 2021
    11.5 Km - rue de Rocroi 102, 6464 Baileux
  • From €35 to €70
    MICHELIN 2021
    14.7 Km - rue de Scourmont 8b, 6464 Bourlers