Iguazu Falls, Argentina/Brazil
Of the Big Three waterfalls, Iguazu is by far the most photogenic and has been featured in a number of movies, including a James Bond film (Moonraker) and an Indiana Jones film (Kingdom of the Crystal Skull). Iguazu is underlain by the basalts of the Parana Traps, a large province of flood basalt covering several hundred thousand square kilometers that began when South America and Africa were still joined. The African equivalent is in Nambia and Angola and is known there as the Etendeka Traps. Iceland is the modern analogue for flood basalts in which hundreds of thousands of cubic kilometers of basalt are erupted onto the surface and covers large areas. The reason for these events is not entirely understood, but they are widespread with similar flood basalts occurring in the northwestern U.S., India, and South Africa.
One of the greatest dangers to Iguazu is the decimation of the Parana rainforest of which it is a part of. Nearly 95% of the forest has been cleared and like the Amazon rainforest, the health of the Parana rainforest has a large impact on water flow through the Iguazu River. Furthermore, the rainforest also affects precipitation and clearing of the forest could diminish regional rainfall thereby diminishing water flow over the falls.
One of the greatest dangers to Iguazu is the decimation of the Parana rainforest of which it is a part of. Nearly 95% of the forest has been cleared and like the Amazon rainforest, the health of the Parana rainforest has a large impact on water flow through the Iguazu River. Furthermore, the rainforest also affects precipitation and clearing of the forest could diminish regional rainfall thereby diminishing water flow over the falls.
The beauty of Iguazu is the diversity of its falls ranging from tiered falls to rows of individual falls seen in this photo to the dramatic horshoe of La Garganta del Diablo where the largest portion of the Iguazu River falls in a single drop into an enormous cauldron of foam.
The Argentine side, of which 75% of Iguazu Falls lies, has a cool network of trails that give you virtually every possible perspective of the falls. Some of the viewpoints are close enough that you will get wet from the spray. The tiered nature of the falls has to do with discrete lava flow events. The Parana basalts were not deposited in a single massive volcanic eruption, but instead were deposited in thousands of discrete eruptions that occurred over millions of years. The planar surface that separates each flow event is a plane of weakness along which erosion is relatively easy. These planes mark the top of each tier.
Another interesting perspective is to ride the speed boats along the base of the falls. It's kind of cheesy, but still worth the ride. The driver will stick the bow of the boat into one of the falls causing the stern to lift (known in whitewater kayaking as an ender). If you ride when the boat is half empty, you can persuade everyone to ride in the back of the boat allowing the driver to stick the bow even deeper into the falls and creating a higher and more exciting ender.
Iguazu Falls also contains interesting wildlife including crocodiles. Monkeys and toucans are commonly seen in the forest around the falls. The Falls are also noted for butterflies which fly in giant, colorful clouds around the sky. They are sometimes so numerous that I saw some get sucked into the airplane engines at the airport. Here, they are congregating on the crocodile's eyes in order to get salt from its tears.
The highlight of the falls is La Garganta Del Diablo, or Devil's Throat, a horseshoe-shaped arc of cliffs over which about half of the flow of the river drops. While the rest of the falls are appreciated for their aesthetic beauty, La Garganta is known for its sheer awesomeness. From the Argentine side, a nearly 2 km long catwalk takes you over the Iguazu River to the edge of La Garganta. Long before you see the falls, you feel it, a deep rumble that you feel in your chest. You can also see the cloud of mist generated by the falls well before actually reaching them.
The viewpoint overhangs the edge of the falls and is close enough that you'll get wet. In the hot, humid Parana jungle, it's actually a relief.
When I first viewed the falls at La Garganta, I was just amazed at the volume of water flowing over the edge. The basalt that holds up the falls is resistant to erosion and the falls are retreating by an average of 2-3 mm/yr. By contrast, Niagara Falls is underlain by soft limestone and is retreating by up to a meter per year. Niagara Falls is expected to retreat to Lake Erie and cease to exist in as little as 20,000 years. Iguazu should still be around for hundreds of thousands of years.
Another boat adventure at Iguazu Falls was offered in the 1930s in which tourists could ride in a rowboat right to the edge of the falls. As the stern of the boat hung over the edge of the falls, tourists would peak into the oblivion of La Garganta. This continued until one rower became exhausted and the current overcame his boat resulting in his death and the tourists riding with him. Understandably, tours were discontinued immediately afterwards.
It's no wonder they call it the Throat of the Devil - you feel like you're staring into nothingness when you look straight down with water falling from three sides. Incidently, although numerous people have fallen over the falls, none have survived. This contrasts with Niagara Falls where people have deliberately gone over the falls. The base of La Garganta is composed of large boulders so that one is unlikely to survive such a fall even in an engineered structure.
Another cool feature of Iguazu Falls is the rainbow created by the mists rising from La Garganta. This appears throughout the falls with some of the best bows seen from the Brazilian side. At La Garganta, the rainbows are strongest in the late afternoon.
Watching all that water fall over the edge is absolutely mesmerizing...
...It's also hard not to imagine what it would be like to take a swim over that edge.
A unique way to see the falls is to go at night. Park officials open the falls during the 5-day period that spans each full moon. The sounds of the Parana jungle are distinctively different than during the day. The falls, though not as spectacular as during the day, are still worth seeing. An interesting phenomenon seen under the full moon are rainbows whose colors are subdued, almost black and white.
Logistics
Iguazu Falls is located on the Brazil/Argentina border. Although it is relatively easy to enter Argentina, Brazil has a reciprocal visa policy meaning that if your home country requires Brazilians to get a visa 90 days in advance and pay a fee, then you will have to do so as well. Generally speaking, however, Brazilian authorities will allow you to cross into Brazilian territory for a day if you just want to view the falls from the Brazilian side (you will have to go into Brazil if you want to ride the helicopters over the falls). Paraguay is also a stone's throw from Iguazu, but it too requires acquiring a visa in advance for most countries.
Iguazu Falls is part of the "Tri-Border" region of Brazil, Argentina, and Paraguay, considered to be one of the most lawless regions in the Americas. Although it is safe in the tourist areas around Puerto Iguazu and Foz do Iguacu, the surrounding area suffers from lack of security and a weak judicial system. Aside from Itaipu Dam, there aren't a whole lot of side trips out of Iguazu,but Iguazu's location makes it a convenient way point as part of a grand South American tour.
Iguazu Falls is part of the "Tri-Border" region of Brazil, Argentina, and Paraguay, considered to be one of the most lawless regions in the Americas. Although it is safe in the tourist areas around Puerto Iguazu and Foz do Iguacu, the surrounding area suffers from lack of security and a weak judicial system. Aside from Itaipu Dam, there aren't a whole lot of side trips out of Iguazu,but Iguazu's location makes it a convenient way point as part of a grand South American tour.