The Salto Yucuma is reportedly the longest longitudinal waterfall in the world (1800 meters or 1,12 miles). It is located on the Brazil-Argentine border in the nature reserve Parque Estadual do Turvo in the west of the southern Brazilian state of Rio Grande do Sul, about 20 km from the town Derrubadas, and in the province of Misiones (Argentina).
The high and 15 meters water curtain is on the Argentine side of the Río Uruguay, but the Brazilian side offers a better look at how the river falls into the basalt column.
In the Tupi-Guarani means Yucuma great event. In the interior of southern Brazil, the state park Turvo is one of the few areas that has not been destroyed by human influence. Even today there live jaguars.
Source: Wikipedia (translated and edited by me from portuguese and spanish versions).
I took this picture on a very hot day, feb. 2012. The work is my own resources.
If you like it, please fave it! Thanks in advance!