In pictures: An epic journey

A British couple, Patrick and Sue Cunningham, are using a little boat to navigate 2,500km (1,553m) on one of the most important rivers in Brazil to discover how climate change and modernity is transforming the landscape and the lives of Brazilian indigenous tribes.

The Xingu River flows through intensive agricultural land before entering the Xingu Indigenous Park. Lower down its course, the river flows through 400km of rapids, barely navigable even by skilled local boatmen.