At the border between Argentina and Brazil, we stared down the Devil's Throat.
There was no fire or hot molten lava, but instead, millions of litres of rushing water plunging into a U-shaped chasm every second, with an incredible plume of mist and spray as high as a 150m above it.
Nicknamed the "Devil's Throat", or Garganta del Diablo in Spanish, this U-shaped chasm is where half of the flow of the mighty Iguazú River tumbles - with metal catwalks on both Argentinian and Brazilian sides of the falls allowing visitors to get up close to witness the violent force of the water as it tumbles down from the Parana plateau.
The rest of the water plunges down at other points of the plateau, and depending on the season, there are between 150 to 300 waterfalls, which collectively make up the mighty Iguazú Falls, one of the seven natural wonders of the world.
Most of these waterfalls are on the Argentinian side of the falls, and are reached through two walking circuits - the lower circuit, Circuito Inferior, and the upper circuit above the falls, the Circuito Superior.
In addition, there is a third circuit on Isla San Martin, an island along the river, which can be accessed when the river levels are deemed safe to land.
We headed for the Devil's Throat first, as we had read that it was the most spectacular part of the falls. To get there, we hopped on the Ecological Jungle Train.
The train chugged along at a snail's pace through the forest within the park, and got to the start of the short trail that led us to the Devil's Throat.
As we stood at the catwalk that looked down at the chasm, we were awed by the spectacle.
Upstream, the river looked deceptively calm, but at the edge of the plateau, it vanished with a roar into the pool of swirling mist and spray below.
Onwards to the Circuito Superior, we stopped frequently at various viewpoints to take photos of the waterfalls and rainbows below us.
This circuit took us through the rainforest, and includes a panoramic view of the Mbigua, San Martin and Escondido Falls.