Iguazú Falls

The roar arrives before the sight — a low rumble that builds as the boardwalk bends towards the Garganta del Diablo, then detonates into a wall of white water that soaks you before you have found the railing. Iguazú straddles the Argentine-Brazilian border across a horseshoe some 2.7 kilometres wide, the river splitting into cataracts by the hundred, their count shifting with the season's flow. Coatis are the walkways' unofficial residents, kept wild and unfed by rule.

The falls pour over the edge of an ancient basalt plateau laid down by vast volcanic flows, and both sides carry UNESCO World Heritage status — Argentina's since 1984, Brazil's since 1986. The Argentine side provides the most intimate encounter: elevated walkway circuits thread the Atlantic Forest to different levels of the falls, from water-level spray to the upper panorama, and boats run beneath the lowest curtains under the park's authorisation, for a full-body soaking. The forest around holds toucans, tapirs and over 400 recorded bird species — seen on their terms, never on schedule — and the park is firm that coatis and monkeys are never fed or approached. The river occasionally takes sections of walkway back; circuits are rebuilt and reopened on the park's clock. The Guaraní named it 'big water' — the most accurate understatement on a continent of extremes.