The secret of the underground (2009)

Dive with us into the mysterious underground of Slovakia. We will walk through unique sinter, charming aragonite or cool ice decorations, which offer us an unusual view of the secrets hidden in the depths of the earth. You will be enchanted by the diverse formations, corridors prepared by water, massive underground halls, narrow canyons with roaring waterfalls or crystal clear lakes. No wonder many of these caves have made it onto the World Heritage List. (distributor's official text)

Unfortunately the movie The secret of the underground is not yet available on HBO Max.