An Amazon Cruise to Determine the Longest River in the World

by Captain Bill

The Amazon River, largest in the world

Which is the longest river in the world, the Nile or the Amazon? This is an earth shaking question for geologists, geographers, and hydrologists. The exploration of these two rivers is full of history, mystery, and legend. “Dr. Livingstone I presume.” I have a small connection to the Nile, and a large connection to the exploration of the Amazon River, so I have taken an interest in this question.

Some of my best adventure memories are the two times I white-water rafted what had been considered the source of the Nile in Uganda. We portaged around category 8 rapids but shot the rest. Two in our group attempted to kayak the category 8s, but capsized each time. In the United States it is prohibited to raft any rapids above category 5. I felt the fear. I would never attempt a category 8.

Recently my boat, Dawn on the Amazon III, was chartered for an Amazon cruise from Iquitos to the Triple Frontier of Brazil, Columbia and Peru, by a family of Polish adventurers on an Amazon Challenge.

Their Amazon Challenge was to trace the path established in 1996, by the famous Polish geographer, explorer, and great self promoter, Jacek Palkiewicz. Using high resolution satellite photos to begin with, Jacek teamed with the Lima Geographic Society to establish a new source for the “mother of all rivers” that temporarily made the Amazon River the longest.

His source and his calculations were later discredited by over 160 miles and the Nile regained the official designation of longest river.

From what I have read about Jacek he would never have chosen a source that would have been the second longest river. He is a longest river type of explorer.

Because of national pride and Jacek’s knack for promotion our Polish adventurers obtained maps and books and set off on their Amazon Challenge high into the frozen Andes, and then down into the tropical rainforest to Iquitos Peru for an Amazon cruise on to the next leg of the journey.

I studied the maps and photos while we were on our Amazon cruise and started taking more of an interest in the problem. It is difficult to determine river length. Not only is it difficult to pin-point the source and the point of actual discharge but big rivers constantly change their course.

There is no doubt that the Amazon River is the largest. It’s volume is greater than the next 8 largest rivers combined according to Because the Amazon River carries so much more water, the action of erosion is greater and the course of the river changes more.

A long horseshoe bend in the river can be cut off, become a lake, and the river can lose miles of length in one hour. During the flood season the channel can change and pick up miles of length.

The outside bend of a river where the current is strongest is called the cut bank. The inside bend is the slip-off slope. Those names describe the near constant action of erosion that eventually causes the course of the river to change.

In the year 2000 National Geographic put out an expedition led ironically by a Polish-American math teacher, Andrew Pietowski. Using GPS they established a new source, confirming the Nile to be the longest river.

In 2006 the “true source” of the Nile was pushed upstream into the swamps of Rwanda. I have doubts about that story. I wonder if they had a hydrologist on board to measure stream flow. Part of determining the source is measuring the volume of water that flows in a given time period. That swamp has very little stream flow.

In 2007 a Brazilian expedition claims to have established a new source proving the Amazon River to be the longest by 65 miles.

An Amazon cruise to determine which is longer, the Amazon River or the Nile River

I think it is safe to say this controversy is not over. For now I am happy to think of the Nile as the longest and the Amazon as the largest. If a team of cartographers want to float and measure in comfort from the upper Ucayali or the upper Marañon to the triple frontier on an Amazon cruise, please remember that I am interested. Keep Dawn on the Amazon in mind.

To read another article on this subject please click An Amazon Cruise from Iquitos Peru to a Festival at the Frontier.

{ 2 comments… read them below or add one }

1 Carlos Norberto Mugrabi February 28, 2008 at 8:24 am

The longest river, wider and more abundant in the world is that Dante Alighieri describes in his “Divine Comedy” called Aqueronte. And Virgilio with its: “FLECTERE SI NEQUEO SUPEROS, ACHERONTA MOVEBO”, one of his first hydraulic engineers. And the old – but not for that reason defunct- Greeks had alerted on to the subject. By Carlos Norberto Mugrabi.

2 Alan Shoemaker March 25, 2008 at 9:56 pm

The determination of what is the longest river has already been done. It is the Rio Amazon.

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