The underground tour of La Cocalière, following a secure route with a guide providing a commentary, is accessible to all age groups.  The temperature here is constant, around 14 degrees, and you’ll discover a living cave that’s still in formation.

As well as the usual calcite concretions, stalagmites and stalactites of various shapes and sizes (including masses and columns), along the way you can admire the disks – circular concretions which defy the laws of gravity.  La Cocalière’s are among the most beautiful and unusual you will find, with fine draperies (or stripes of calcite) with semi-transparent growth striations hanging from the roof, not forgetting the eccentric budding crystals and long, fine fistulous or macaroni stalactites.

All these geological curiosities can most often be seen in the clear or blue-tinged water of the gours or natural pools, the edges of which are festooned with calcite.  The ones in the Chamber of Gours, which are staggered like a staircase, are remarkable.  The niphargus, a kind of small, blind prawn, can sometimes be seen in the water, particularly in the Chamber of the Bivouac Camp.  A cave pearl in formation will catch your eye as you pass through, especially as this is a natural phenomenon which is very seldom seen.

From the morphological point of view, the cavity is shaped like a long corridor that goes on for one kilometre.  In certain places, the corridor widens to form evocatively-named chambers: the Chambers of Congress, of Columns, of the Puits de l’Aventure, of the Three Kings and more.

Here and there, you’ll also notice that the rock has been cut up by the corrosion caused by the water, which has high levels of carbon dioxide.  This erosion phenomenon, called diacid, creates sharp, pointed shapes in the overhanging cave walls and roofs.  The shapes are softened by the physicochemical action of flood water in particular, as this is often turbid and abrasive.

Finally, while ochre tones dominate the colour scheme, touches of whites and greys are not uncommon.  And the sparkle on some rocks, which is due to large calcite crystals reflecting the light, well and truly makes La Cocalière “the Diamond Cave”.

Your underground tour is coming to an end but before you go back up to the surface, near to the exit you can see representation of a prehistoric excavation site, showing objects and bones from the Neolithic period and the Bronze Age.  From there you can take a little train back to the reception area, travelling along a railway through the garrigue.