Many bombastic claims circulate about Pongo de Mainique. It has a reputation as the most dangerous rapids in South America, and is said to have some of the highest levels of biodiversity in the world. It’s also viewed as a highly spiritually charged location and is English comedian and travel writer Michael Palin’s favorite places in the whole wide world.

First of all, as the name may not be familiar to everyone, Pongo de Mainique is used to refer indistinctly to both a gorge in the Vilcabamba mountain range and the rapids of the Urubamba River that are formed in this gorge. It would make sense to think of Pongo de Mainique as an area including both the canyon and rapids. This is the exact place where the Andes and the Amazon basin meet.

Pongo de Mainique may or may not be the most dangerous rapids in South America, but it is certainly dangerous. (Ranking rapids according to the danger they represent is doable, but it entails a certain degree of subjectivity and falsifiability.) The rapids are only navigable between May and October, and even at that time, you need experienced boatmen with extensive knowledge of Pongo de Mainique. Prior to tackling the rapids, it is customary for boats to make a quick stop at a makeshift landing and let the passengers off the boat to pray for a successful passage.

The area is as beautiful as it is daunting. The six square miles of forest around Pongo de Mainique have indeed an “extraordinarily high” level of biodiversity. Whether you’re ascending or descending the rapids, you are unlikely to see any fauna, as you’ll be busy holding onto the boat for dear life. There is, however, a clear sense that the forest changes at the entrance of Pongo de Mainique. The river narrows and the shore seem to struggle to contain the vegetation, which overflows on the water.

As for the claim to mysticism, it goes back to the Incas, to whom Pongo de Mainique was a holy place. Inhabitants of villages up and downstream maintain that their long-gone ancestors believed the huge vortices created by the strong currents and the boulders were a portal to another dimension. In more recent years, these beliefs have been revived by new age spiritual seekers.

And finally, Michael Palin. In a 2006 piece in The Guardian, Palin mentioned Pongo de Mainique as his favorite place in the world, remarking that, “It really is like being in an antediluvian paradise.” And if this is the time for name dropping, Werner Herzog shot some dramatic scenes of Fitzcarraldo at Pongo de Mainique.

Pongo de Mainique is difficult to reach and even more difficult to get through, but its raw beauty is the stuff that you see in CGI movies.