Iguazú Falls

Iguazú is not one waterfall. UNESCO describes a system some 80 metres high and 2,700 metres in diameter, dropping in a series of cataracts along a horseshoe of basalt on the Iguazú river. The river forms the border, so the falls belong to two countries at once: Iguazu National Park on the Argentine side was inscribed on the World Heritage List in 1984, and the contiguous Iguaçu National Park in Brazil followed in 1986. Together the two protected areas cover roughly 240,000 hectares of subtropical rainforest, of which the Argentine property accounts for about 55,000.

That split is the single most important planning fact about the place, and the one most often discovered too late. The two sides are not alternatives offering the same view from different angles. They are different experiences of the same object, and seeing only one is a legitimate choice, but it should be a choice, not an accident.

UNESCO inscribed the park under criteria (vii) and (x): outstanding natural beauty, and significant natural habitat for in-situ conservation of biodiversity. Both are visible on an ordinary day's visit.

The beauty is not subtle and does not need arguing for. The biodiversity is easier to miss: the subtropical forest the walkways cross holds toucans, capuchin monkeys, caimans in the quieter channels, and (if you are extremely fortunate and very early) traces of jaguar, which the park exists in part to protect. Most visitors see the water and walk past the forest.

This is a subtropical rainforest and rain is possible in every month, so there is no dry season to aim for. What varies is heat, crowding and river level.

The southern summer, December to February, is hot, humid and busiest; it coincides with Argentine and Brazilian school holidays. The shoulder months, roughly April–May and September–October, are more comfortable for walking several hours of exposed boardwalk.

River level is the wildcard and it cuts both ways. After heavy upstream rain the falls are at their most powerful, but the Devil's Throat walkway and the boat trips are the first things closed, and closures have lasted days. In an unusually dry spell the flow drops and the spectacle diminishes. Neither is predictable months ahead, which is the argument for a spare morning rather than for a particular season.

Three broad options, and the trade-off is the same in each country.

Puerto Iguazú is the smaller, quieter town and the closer base for the Argentine circuits. Foz do Iguaçu is larger, with more choice at every price level, and is the more convenient base if your flights are Brazilian. Staying inside either national park puts you at the falls before and after the day-trip crowds arrive and leaves, which is a real difference in experience, at a correspondingly different price.

Whichever side you sleep on, factor the border crossing into the day you visit the other one.

Two towns and two airports serve the falls, one in each country.

On the Argentine side, Puerto Iguazú is the base, served by Cataratas del Iguazú airport (IGR) with domestic flights from Buenos Aires. Note that those flights normally use Aeroparque (AEP) rather than Ezeiza; see Argentina for why that distinction matters if you are connecting from an international arrival.

On the Brazilian side, Foz do Iguaçu is the base, with its own airport (IGU) and domestic connections within Brazil. It is the larger city of the two.

The towns are linked by road across an international bridge, and transfers between them are routine and frequent. Crossing it is a formal border crossing, not a park shuttle.

Inside the Argentine park, the ecological train and the walkway circuits are the transport; there is no driving between viewpoints. Inside the Brazilian park, a shuttle bus runs from the entrance along the road to the trailheads and viewpoints, and it is the only way to move between them.

Between the two towns, buses and taxis cross the bridge regularly. A vehicle rented in one country may not be permitted to cross into the other without additional documentation from the rental company; confirm before assuming, rather than at the border.

The Argentine side

Argentina holds the majority of the falls and puts you among them. A network of raised walkways (an upper circuit along the lip of the cataracts, a lower circuit beneath them) brings you close enough to be soaked. A short park train runs to the walkway leading over the braided river to the Garganta del Diablo, the Devil's Throat, the largest single drop in the system.

The Brazilian side

Brazil holds the panorama. A single main trail runs along the opposite bank and delivers the wide view of the whole horseshoe that appears in every photograph of Iguazú, including the ones taken by people who then discover they were standing in the other country. It is shorter and takes a fraction of the time.

The forest and the river

Boat operations run beneath the falls from the Argentine side, and forest trails such as the Macuco track lead away from the crowds. Both are separately ticketed and both are subject to closure when the river runs high.

The tri-border area where Argentina, Brazil and Paraguay meet has a mixed food culture: Argentine parrilla, Brazilian churrasco and buffet-by-weight, and Guaraní influence in the region's staples. Mate is drunk on both sides of the river; in the heat it is often taken cold as tereré.

The Guaraní were the region's inhabitants long before either national park existed, and the name Iguazú is theirs: from y (water) and guasu (big). Guaraní communities live in the area today and some operate their own visitor projects.

The costs are the two park entrance fees, transport between the towns and the parks, accommodation, and any separately ticketed activity such as the boat trip. Entrance fees are set by each national park administration, differ for residents and non-residents, and change; check each park's official site close to your travel date rather than relying on a figure quoted anywhere else.

The heaviest optional cost is usually the boat trip, and staying inside a park rather than in either town is the single largest accommodation step up.

There is no permit to obtain in advance for the falls themselves. The complication is national, not conservational.

Visiting both sides means entering two countries. Argentina's entry rules do not apply to Brazil and Brazil's do not apply to Argentina: a passport that enters one visa-free may need a visa for the other, and the answer depends entirely on your nationality. Check both sets of rules separately, with each country's own authority, before you plan a two-side visit. Travellers have arrived at the bridge and been turned back over exactly this.

Each park charges its own entrance fee, payable at its own gate, and each sets its own rules on multi-day re-entry, opening hours and last admission. Fees and conditions change; the national park administrations are the authority for current figures, not third-party sites. Boat trips and other in-park activities are priced and booked separately from admission.

You will get wet on the Argentine lower circuit and thoroughly soaked on a boat trip. Bring a dry bag for anything electronic rather than trusting a phone's water rating against Iguazú's spray.

Coatis, raccoon-like animals that patrol the walkways and picnic areas, are habituated, persistent and will open a bag. They bite and scratch when food is involved. Do not feed them, do not pose with them, and keep food closed and inside a bag.

The walkways are long and largely unshaded. Sun protection and water matter more than most visitors expect.

Closures of the Devil's Throat walkway and of boat operations happen for high water, without notice, and are not appealable. Building one flexible morning into the visit is the only real protection.

Two days, based in Puerto Iguazú. Day one: the Argentine park at opening, upper circuit, lower circuit, train to the Devil's Throat in the afternoon when the morning tour groups have cleared. Day two: cross the border early, walk the Brazilian trail, return in the afternoon.

Three days, adding depth. As above, plus a boat trip and the Macuco forest trail on the Argentine side, or an early morning back at the Devil's Throat if the first attempt was closed.

As part of a longer Argentina trip. Iguazú fits naturally as a two- or three-night detour by air from Buenos Aires, in either direction between the capital and Salta or the northwest. It does not combine well by land with Patagonia; the two are at opposite ends of the country.