It is the longest river in the world but it has no bridge. The Amazon river crosses nine countries from east to west on the South American continent. Between 350,000 to 500,000 people live along the river. However, to access the other bank, the inhabitants must go there by boat. No bridge has been built over the river because the depth, the width, the power of the river are binding elements for any construction. For instance, during the rainy season, the river level can be 15 meters higher than during the dry season. Photo credit: Ivars Utinans