Ah! Visiting cavities! Fascinating... why: because these obscure places are part of the last mysterious places, and numerous 'premiers' happen each year! And luckily for us the Grands Causses house over 2000 cavities... and how many others are there, still waiting to be discovered? Progression underground doesn't necessarily mean going through ridiculously tight gaps in the mud... luckily! It is also possible to take part in visits in the heart of the Earth using large galleries, discover underground lakes and contemplate unique concretions in comfortable conditions. Equipped with wetsuits, boots and an acetylene light, all you have to do is follow the guide.