ABSTRACT
The Peruaçu area has been ranked among the most scenic karst areas in the world. Its highlight is the outstanding Gruta do Janelão, a 4.7-km long cave that contains a major river passage up to 100 m wide and high (Figure 2). Collapse of the roof has created a series of scenic skylights that allow the entry of natural light and growth of tropical vegetation within the cave, creating an exceptionally beautiful underground landscape (Figure 3). Massive speleothems occur throughout the passage. The Gruta do Janelão is the last cave excavated by the allogenic Peruaçu River. The other three caves upstream
