The Amazon River is famous for its vast jungle basin, breathtaking waterfalls and the world’s largest species of river dolphin. It also hosts up to 60 different species of piranha. But it’s a mystery why no bridges cross the river, which runs through three countries and whose basin is home to over 30 million people. Is it because of the fundamental challenges in building such structures in a rainforest with swamps, extensive wetlands and thick undergrowth? Are there financial obstacles? Or is it simply that it’s not worth the effort?

According to Walter Kaufmann, a structural engineer and professor at the Swiss Federal Institute of Technology Zurich, there are a few reasons why there are no bridges over the amazon. For one, the river’s wetlands and soft soil would require ‘extremely long access viaducts and very deep foundations’ which means a huge financial investment, as per Unilad. Additionally, the pronounced differences in water depth which occur between seasons would render pontoons unfeasible.

In addition to that, there’s little demand for a bridge in the area. Most people living along the river live in smaller towns and cities where boats and ferries have been established as transport options for crossing the river, so they see no need for a major upgrade.

Finally, a bridge would be an eyesore in the beautiful and wild landscapes which surround it, and could have negative impacts on wildlife, especially since it would disrupt natural ecosystems. For all these reasons, it seems unlikely that a bridge will ever be built over the amazon, even though there is one large bridge which crosses one of its primary tributaries called the Negro River.