Brazil has at least 3,000 caves officially identified – and some of them are absolutely phenomenal. You will find here a selection of images found at Flickr. You should also visit Fotografia magazine’s website to check 20 years of underground photos by Alexandre Lobo.
In case you are wondering, the best source online of information about these geological formations is the Sociedade Brasileira de Espeleologia website (unfortunately, most of it only in Portuguese).
Also, read the post Maquiné, the cradle of Brazilian paleonthology.
These are really some of the prettiest caverns we have there.