After just 20m it’s possible to see the famous Stone Age bulls on the wall… If you can find your way in, that is. The cave has been closed to the public since the 1963.
Just 30m into this grotto, you’ll start to see evidence of Arachnocampa luminosa – or glowworms as they’re more commonly known.
One of the longest cave systems in the world at 222km, it’s stunningly beautiful. Think 6m gypsum chandeliers and cave pearls.
A climber’s paradise. After 500m of transverse descent, you come to the eerie stalactite formation known as the Salle des Treize.
Known as Elsa’s Ice Palace, only the first kilometre of this pure ice cave is accessible. Beyond that, it’s Elsa only.
Dug in 1943 by Polish slave labourers who, to the Nazis’ chagrin, not only refused to die but actually got stronger. All as a result of the mountain’s (slightly controversial) radioactive healing powers.
Jungle gym: 6km into this vast cave you’re confronted with a wall 60m high, which has only just been conquered by mountaineers.