The Saint-Jean Engelsbourg silver mine – known as the “Colonne Saint-Jean” – is the largest man-made underground cavity in the Vosges massif. A 180 m3 cavity 120 metres high. The Tellure Mining Park offers to explore its every corner in caving mode, with wetsuit, boots, helmet, and harness provided. In total, seven routes are available, adapted to the level of each person, with an average duration of two hours. However, the longest tour requires a six-hour stay in the mine. State-qualified speleologist guides accompany the apprentice cavers.