Before going deep underground, you need to get in shape, and the brand-new “Vidéokarst” film will do the job nicely, combined with the Val d'Enfer research laboratory. Then, an impressive descent will take you to the Salle du Sabbat. At 60 metres underground, the bewitching echoes of sound and light will accompany the slow rise of a hot-air balloon…Now's the time to come and experience it!