Puerto Maldonado, in Peru's south-eastern Amazon region, feels like the end of the road. In this hot, dusty town 500 miles east of Lima, young men on motorbikes scour the streets looking for taxi fares. Cars cannot handle the dirt-and-pebble roads.

Small motor boats ferry passengers across the Madre de Dios river, a tributary of the Amazon. Beyond it, a track leads 244km north through the jungle to the border crossing with Brazil.