Courtesy of Ricardo Ratto in Palmas, Brazil.

Between the Amazon rain forest and Brazil’s coastal savanna, the city of Palmas is site of a 8 km cross-river challenge.

The competitors start off together in a large pack and then gradually separate along the Tocantins River.

Its trophies, bunched together on a table, give an impression of pack swimming.

Copyright © 2014 by World Open Water Swimming Association