The region’s limestone rock formations have given rise to canyons, underground caverns and caves, some of which have imploded. The best known is Buraco das Araras, a 124m deep and 500m wide sinkhole created by a collapsed cave near Rio da Prata. Many red-and-blue macaws (and other bird species) have sought refuge here, loudly chattering in trees as they watch over their nests wedged in amongst the cliffs below. The observant eye may even spot caimans in the muddy waters at the base of the sinkhole!

The tour starts at the reception with a brief explanation of the geology and natural history of the sinkhole, and then proceeds along a circular trail along the rim past two observation decks. Macaws can be seen here throughout the day, but are most active at dawn and dusk, when they leave or return to their nests from foraging.