most caverns usually originate from the interaction between rock and water, as water over time slowly dissolves the ground and leaves behind an empty space - sometimes these spaces are large enough to allow people to enter and explore.

the formations we find in the state of rio de janeiro were formed in this fashion - being situated in a very humid area, water constantly erodes the ground, which over thousands of years, will result in cave formations. famous stalactites, complex labyrinths filled with crystals, underground rivers and exotic creatures are but a few of the marvels the exploration of caves can offer.