What is the longest river in the world? A new expedition aims to resolve the controversy

Dubai, United Arab Emirates - In our modern era, it may be fair to assume that science has conclusively answered some questions about the natural world, or at least those that rely on physical measurements. However, there is a question, although it is clear, it is still confusing: What is the longest river in the world?

In fact, science is still struggling to answer this question. The Nile River in Africa has been officially awarded the title of “the longest river in the world” by reliable sources such as the Encyclopedia Britannica Limited and the Guinness Book of World Records.

But an upcoming Amazon River expedition - undertaken by a team of international explorers and researchers - traveling by raft, horses and boats covered with solar panels - is poised to question that classification. Yuri Sanada, the 55-year-old Brazilian expedition leader, an experienced explorer and film producer, recounts his colleague's metaphor for the size of the Amazon, which carries four times more water than any other river: "The Nile is like a worm, while the Amazon is like an anaconda."

He continues: “So there is no comparison between them. We already have the largest river, but as for the longest river between them, we will see that.” The planned five-month expedition, scheduled to launch in April 2024, aims to travel the entire length of the Amazon River, using modern satellite technology to map the river and scientifically prove once that the Amazon is not only the largest river in the world, but the longest.

It is worth noting that the Amazon River is not a single stretch of water, but rather part of a larger “river system” that extends over much of northern South America. The disagreement over its length stems largely from the question of where the Amazon River begins.

While Britannica and others have traditionally measured the river as starting at the headwaters of the Apurimac River in southern Peru, American neuroscientist-turned-explorer James Kontos, 51, claims to have discovered a farther source, the Mantaro River in northern Peru, while searching for river rafting routes in the country. “I was aware that the most distant source of the Amazon River was considered the Apurimac River, but while collecting information, maps, hydrographs, etc. in preparation for my trip to Peru, I realized that another river seemed longer,” Contos says.

He also verified this information using topographical maps, satellite images, and GPS measurements while kayaking there, and published a paper on it in 2014. “The discovery of the new source adds 77 kilometers to the length of the Amazon River compared to the source that was previously viewed,” Kontos noted.

Contos' findings provide the expedition team with "an excuse to be there," Sanada said, explaining that while mapping the river is its ostensible goal, the expedition has larger goals to fully document and highlight the rich biodiversity of the Amazon rainforest region, and the need for the global community to work together to help preserve it. The planned expedition's route will span 7,000 kilometers along the course of the Amazon River through Peru, Colombia and Brazil, starting at its newly claimed source at Mantaro, deep in the Peruvian Andes.

The expedition will paddle across the waters of Mantaro on a raft led by Kontos; Once the Eni River meets the Mantaro River, the longest part of the journey will begin on three specially designed solar-powered and pedal-powered boats, which will follow the remainder of the Amazon River up the Atlantic Ocean, on the Brazilian coast. Sanada pointed out that in early 2025, there will be a secondary expedition starting from the Apurimac River in Peru, the traditionally recognized source of the Amazon River, which will allow for second measurements.

Now, Sanada oversees a team of about 50 project collaborators from across the Americas and Europe, and the expedition has already secured some prestigious partnerships such as support from the Explorers Club Association, a deal to produce a related film with IMAX, and a commission to produce a new map of the Amazon River for Harvard University. Sanada explained that the mission will also host a rotating team of international scientific researchers from participating universities in Brazil, Peru, Colombia, the United States, and other countries, who will join at different stages with the aim of introducing sustainable technology to traditional Amazonian communities.

He added: "These projects will teach them how to treat water, techniques for building better homes using natural materials, obtaining electrical energy from renewable sources, waste treatment, electric transportation, and more, which will change the lives of the residents there." Whatever the outcome of the expedition, Sanada said he would like to explore the Nile next, using the same techniques and measuring methods.

The Nile River, which flows through northeastern Africa before reaching the Mediterranean Sea via Egypt, faces controversy over its source, as more than one African country claims that the river’s sources pass through it. After the expedition is completed, a full documentary and IMAX film are expected to be released in 2026.

Sanada believes these projects can help boost regional pride, international tourism, and thus conservation efforts in the Amazon, by showing “how valuable they are, and why we should preserve them.” “It's all about the search for knowledge,” Sanada emphasized.

"We will show the world what the value of the Amazon is."