Why Nobody Knows the World’s Longest River

As a Brazilian, I will accept any measurement that shows that the Amazon is longer than the Nile, even if you have to count Pedro's toilet pipes that dump into the river to increase its length.

If people are going to count the curve around Lake Victoria, why wouldn't the Amazon River count the southern route?

Elementary school: The Nile River is the world's longest river!
RealLifeLore: Are you sure about that mate?

I'm from Colorado and I've hiked the tallest mountain in Colorado. The highest mountain and second highest mountains in Colorado are neighbors and there is only a difference of 10 feet between them. The two mountains are Mt Elbert (14,439 feet) and Mount Massive (14,429 feet). Here, it is tradition for many hikers to take a rock from the base of one of the mountains and carry it all the way to the top of their respective favorite and deposit it at the top. My rock is on the top of one of the mountains. I can't tell you which other than the fact that it is the tallest. I am suggest that surveyors of the respective Amazon and Nile rivers bring shovels with them next time. When they get to the source of their river... start digging.

Instead of breaking the length in smaller parts of 10 KMs, you should have broken down into the lengths of Toyota Corolla

I think there's some problems with what's being described here. Definitions of rivers aside (which _is_ a big issue; like whether lake Victoria counts as part of the river), there's no fractical problem and not much other measurement problem. You just need to measure the shortest distance possible. No running along the edge of land, and hence no fractal problem. When it does encounter land it only hits the "pointiest" tips, so it doesn't get much worse the more you zoom in. Sure there's still the issue of water levels changing the measurement distance, but that can be dealt with in it's own way (like measuring at max an min)

Rivers are not infinitely long, even if you use infinitely small measurements. In mathematic, there is a concept known as limits. I can understand the issue with measuring some rivers, like the Amazon, because they have so many tributaries. But the curves would only cause the river to reach a limit of so long.

Coastline paradox arises mostly from lines heavily zig-zagging in tiny scales. But rivers are not one-dimensional lines, they have widths, so I believe the paradox can easily be avoided with carefully chosen definitions. For example: given two points A and B on the river, the distance between A and B is the shortest distance one would have to travel while remaining on the river surface. That should smooth out any zig-zags. Now all you have to do is choose such A and B that would maximise the distance (B obviously should be adjacent to a sea or ocean). That should not only bypass the coastline paradox but also prevent such "tricks" like adding the lake coastline instead of a shorter path across the lake.

The narration, the hard work done by the team, and especially the editing is just extremely good.

We all know who found the true source of the Nile: Jeremy Clarkson, James May, and Richard Hammond.

My rules for river measurements:
1, Take the longest continuous waterway that exists in the same river system. (Despite what name it is called)
2, Measure the length of the actual riverflow, like you were on a ship following it. So yes, every curve counts, and not just the distance that the river bridges across.
3, Always use the river's center line for determining the river's length.
4, Always take the longer rout around islands, and at the river's mouth.

I'd measure it by shortest travel distance (as if by boat). This would jump edge to edge of the river, but would at least be consistent for all rivers, and take into account any amount of bending. It also has a reasonable reason for measuring this way; if you wanted to travel the river by boat or kayak, this is the minimum distance you would have to travel.
It doesn't entirely eliminate the "make the segments shorter and the river gets longer" problem, as you still have to travel the inside curves of river bends. :/

The fractalness of water is easy to see. Just realize that every stream of water is in itself just like a river, feeding into an ever bigger river. They're all the same, but just at different sizes. Which explains why you can't truly measure the longest river, as you'd never be able to stop with each infinitisemaly small stream, which are always changing in lengths, sizes, and paths.

I don’t think the limit of the river’s length as you reduce the unit to 0 is actually infinite. It will just approach the true path length of the river, which is kind of like a line integral over that curve. Rivers aren’t infinitely nested repeating fractals, contrary to the analogous image you showed lol.

Let’s take the moment to appreciate how much effort RealLifeLore puts into his content for us. Great job

A different, albeit pretty impractical, method of measurement is to release a floating tracking device, record the distance and route it travelled, and then re-do the process to refine the result. Ideally, this process would be done hundreds, if not thousands, of times until the average distance through every tributary and distributary (where the river splits to 2 or more different rivers, usually occurs at rivers' deltas, but could also happen before that).
Although it isn't the end-all, be-all solution -- for example, what would happen if the device enters a lake, floats aimlessly on the lake's surfaces, increasing the measured distance, before flowing out from the lake's mouth into a different river? But this method might help to better understand the distance a water droplet travels, the likely course, the volume, and the duration.

The problem is that they don't have clear rules to measure the rivers length because I think when measuring the length they should take the widest tributary for example not just the one that will make the river longer

I used to have a "mileage pen" that when rolled across a map would give the number of miles from start to finish. I expect that a more precise and accurate sort of device could do this measuring- and all one would have to do is run it on the length of a river.
This would certainly tell one how far one would travel when following the river from start to end. That's not "really" the actual geographical length of the river, I suppose, but it would tell you how far you'd have to sail to get up or down it. That seems to be the real meaning of "longest" river in practical terms.

As a human, whose ability to conceptualize comes from my experience as a human, I think the standard unit should be a small vessel, say 4m, riding centered between banks (in cases where the water splits and comes back together, it should be whichever channel is larger). This, to me, would give the lengths meaning. This doesn't happen with road lengths, or the distances between cities. Also, I chose 4m for the length of the vessel/resolution, because I had a 12 foot long alumicraft and it was the perfect size for a couple friends and a case of beer.

I understand how fractals make it impossible to get a precise measurement of the length of a coastline but for rivers there must be smarter options.
My suggestion: you send lets say 100 small GPS tracked floating devices down a river, measure how long the path was each of them took, middle it out and that's your length. For this you only need to reach one accepted consensus on where a river starts, after that you'd have only numbers and no more opinions.
Something similar can't be applied to coastlines but everyone could agree that it makes no practical sense to measure a coastline in any smaller fractions than 10 metres. Once everyone uses the same denominator you will again be able to compare results.
Of course this information is of questionable value, it's not scientifically valuable and if we are only using it for country cock comparing contests then the time of scientists is probably best invested elsewhere.

I love rivers man. They're like natural magical roads through the wilderness where you can float and explore until the end of time.

When a river takes multiple paths from point A to Point B (for example, around an island), shouldn't you take into account how much volume of water flows along each branch? Either choose the branch with the most flow, or take a weighted average of them.
This could easily be used to decide where the "endpoint" of the Amazon or Nile river is (or at least the average distance from the last comon point and the ocean). It is less useful for determining the staring point of a river.

Personally I feel like the length of a river should be the addition of all of the tributaries put together. Kinda like, if you wanted to travel on every section of the Nile, how long is your journey, not counting cut backs to go over bits you've already been on. Just feels more intuitive to me. Like say you have a 'map' of a river made with string, with obv separate strings connected where they diverge and converge. I feel like the length is how much string you need, not how much is the longest uncut piece of string you have. Wrt lakes I feel like they should pick a mid point and travel in a straight line through the midpoint when the river travels through the lake. Although picking a midpoint is always controversial, but I'll think about how I want to define that later.

I just have to say that the Amazon River is so beautiful, its like a paradise. Amazon rainforest is a truly beautiful place, protect it!

"The length of the river approch to infinity as you take smaller measuring units"
The length of the river doesnt approach to infinity as you take smaller units, it approaches to the actual length. Also, taking smaller units to measure doesnt necessarily increase the length of the river.

The major tributaries should definitely be considered when determining the length. They are afterall needed for bifurcation ratios.

Something : *exists slightly bigger than France
RealLifeLore: *laughs in evil

"Honey, I'll go out expedition to measure a river length"
"Fine, but don't get too political"
"I won't"

I would say the most fair way to measure is the following: imagine you have a really long measuring tape. Put it in de water, as long as you can continue rolling it out in the water, *as long as it stays stretched*, that measurement is the legal. The longest possible road can be taken.
That way al branched are considered and no stupid bends are legal.

Yesterday, I happened to be looking at a map of the Big Blue River in Kansas and Nebraska. It's a tributary of the Kansas (Kaw) River. It rises near Aurora, Nebraska and flows into the Kaw at Manhattan, Kansas. It flows about a half-mile from our house, on its way to Marysville, Kansas where I'm originally from. It's about 60 miles by road between the two. I wouldn't even want to guess how long the river is between the two points, but I would 'guesstimate' somewhere between two and three times that far.

In short we just need standardization. Taking account into the best measuring unit, how to define the source and the end of a river, the tolerance of change in length of river over time, yada yada, etc. I believe someone in geology field must have done intensive research into all these, but political influence must have get into the way of reaching a conclusion.

The main stream is the way most water run through. Then the scale must be the same for all compared rivers. Still a strait river vs a very meander rich one may be much different depending on scale. You need to set an international standard as many other technical things.

I kinda wish we had EXPANDING river measuring instead, where the winner decided by the wide of the mouth of the delta.
because, it's not how long but instead how better and more skillful you can use your river; also, thicker is better.

Adding the Missouri river to the lower Mississippi does NOT 'triple' the length because you have to subtract the upper Mississippi then. 3760 is NOT triple of 2348 miles.

Thank you so much for uploading this video. It is helping me get through the pandemic!

"you could measure more and more molecularly and your answer would keep moving towards infinity"
what? how?? technically it keeps moving up, which is the direction of infinity, but it would not imply infinity in the same way that it would move towards the mathematically perfect answer that you could get from measuring the river in the way that you choose. maybe this was supposed to mean "your answer could change infinitely depending on how granularly you decide to measure it" and that would be true, but isn't the solution to this just standardization??? this feels like armchair philosopher "deep" talk trying to sound intellectual instead of a practical discussion of measuring the length of rivers.

We all know, James May is the discoverer of the true source of the Nile.

The amount of distance you travel walking aside it from the start to the end should be the indication of its length and the longest ending point since it’s still part of the river should indicate the end and start of the rivers

The important question to ask is: Did you measure from base to tip?

Love your videos! I’m in my schools quiz bowl team, and I learned most of it from you!

I always love your content! Please keep it up

I always thought it was silly they included Lake Victoria into the measurement. Lake Victoria is, well a lake, and while the source, does not constitute the river. It's measurement should be at the mouth of the where the two meet.
I did some quick measurements on google maps, and according to that same logic, the Great Lakes system and the St. Lawrence seaway would make a 2500 kilometer "river".

I guess it's kinda arbitrary which river you consider longer so I just like to say it's the Nile because the Nile is important to so many people and so much of history. The Amazon is already winning the most water title easily.

is there a similar controversy for the measurement of the world's longest road? road systems probably fit the same criteria and have the same problems as rivers, only theyre manmade

Minnesotan here, it was cool to hear Lake Itasca mentioned! Although I should point out it's pronounced "Eye-tass-ka". There's also some controversy as to if it's the real source of the Mississippi. Many people consider it to actually be Lake Nicolet, which is connected to the opposite end of Itasca by a small creek.

Virgin “longest River fan” vs Chad “largest watershed by annual rain volume”

Personally, I think you should measure the length of a river by measuring how long a semi-sized boat would have to travel to get from one end to the other, and if it branches you should follow the biggest branch. Still, it doesn't really matter as you should always state precisely what you are measuring and what branches you have used

"The length will approach infinity as the measuring units get smaller."
*frantically goes to measure pp on the molecular level*

I have an idea of how to measure River length:
Step 1: get boat
Step 2: get odometer
Step 3: drive boat with odometer from start to end of the River

The claim that you could measure up to infinity is not true, as it would be physically impossible to use units shorter than the Planck length. So there is a limit.
Also not mentioned: do you measure along the Thalweg (which constantly changes, along with meanders), the center line, or some average of the length of the left and right banks?

Wouldn't measuring a river on the molecular level make the measurement more precise instead of a huge number?

A river's length changes throughout centuries. This is because silicate and other minerals erode on one side of a river than the other. This erosion leads to a concave side, the side with harder, more stable minerals; and a convex side, the side with more erosion. This leads to a curve or bend in the river which increases throughout the ages, thus increasing the river's length. When the curve reaches a point where the two ends of the curve meet, they form an oxbow or horseshoe lake which is independent from the river. The river then returns to a straight line, thus its original length. New channels and merging rivers could also be formed by erosion, though this is rare due to the variation in thickness and hardness of soils and minerals surrounding the river.
In theory, the Nile is longer in length than the Amazon, which leads to more curves therefore longer. Overtime though, this varies and the length of the river also varies. It depends when the lengths of the rivers were recorded and how precise the measurements are.

Just run a program to find the fastest path throughout the river, and have the discovering end when it hits the end. Then from all the points scanned, find the shortest route

This reminds me of a video I watch discussing the length of the US coast line and dispute on what country has the largest coastline in the world. Wish I could remember who made that video.

I have a solution. If main river has two or more smaller rivers attached to it, do not go by the measurement of lengthiest one but take the length of the main sub river (which carries more water to main river). In this was we can avoid measuring small small sub rivers or streams which is giving less volume of water.

wouldn’t the length of the river just approach a limit? i know it can’t be definitively calculated.. but it would simply approach a limit, not infinity

My geography teacher gave us once a similar task to measure length of a river, but we had to do it with a string instead, so we could bend it to the shape of that river

Oh, Jeremy Clarkson, Richard Hammond and James May found the source of the Nile about ten years ago. Made a whole documentary about it that’s quite entertaining.

Personally, I find it really odd that we name one piece of a river system with a particular name but then name other parts by a different name. I mean, we obviously get that they're all the same river system. I mean, it's called the Mississippi River Basin after all. Shouldn't the entire thing just be called the Mississippi river? We don't say, oh.. the Pacific Ocean isn't actually the largest ocean, because it includes the South China Sea, which China won't allow us to include in the Pacific Ocean because that would imply it's not exclusively theirs.
Of course, I suppose that metaphor breaks down a little when you have to then extend it to rename all the oceans in the world with the same name.

The tributary issue is a definitional one, and real. The fractal measurement issue is easily ("easily") resolved in the case of a river though - you take the shortest route along the river (i.e. imagine you stretch a string between source and end, and stretch taut).

Great exploration and explanation of history of rivers. 🏞

RLL: "The length will approach infinity as the measuring units get smaller."
Integral calculus: "Am I a joke to you?"

I traveled by boat up the Amazon and could not see the shores for a very long time! Loved the trip.

I would enjoy these videos more if you also used miles, feet, inches when describing distance.

I would say it’s the Amazon River is the longest. I’m with you when when it comes to cooking. My knives are terrible. My sone bought these knives for me for Christmas. They are the best! It seems I waist a lot of food so I’m going to have to get a service for that also. I hate shopping of any kind. The grocery store where I live are terrible. Small & very crowded. Thanks for all this!!

I thought this video seemed familiar because Atlas Pro made one similar 3 years ago. Both are well made. Keep up the good content.

3:57 This statement is misleading. Infinite chunks of infinitely small size don’t necessarily add up to infinity (see also: Zeno’s Dichotomy Paradox). It is well within the realm of possibility that as you approach infinitely small measuring steps, you also approach a fixed value.
This is also true for coastlines. The number approached will be very much higher than a more useful value, but the value “increasing to infinity” is kinda a thing people just say that they assume is correct. Fractals have an infinite scope, whereas the world has a fundamental smallest length.

So, here is my rule for river lengths!
So, if a river connects to any other river, that river will not count, all of the main entrances of a river are counted and if the river ends to a lake, it must go to the northern, southern, western or eastern most point of the lake.

3:40 similar to the coastline paradox

Why would you use small blocks of that river?
Use a string then measure the string piece used and convert based on whatever the map scale is.

Serious question. Does a river's length qualifies as a coastline paradox?
Why not take a satellite photo, draw a continuous line following the river and measure the length of said line using a software?
While yes, a river's topography changes over time, a date can be added to show when the length was measured.

Even though the last research was done by the Brazilian geographic society, but it looks reasonable enough to me. Unless the Egyptian geographic society could find a hidden small tributary for the Nile River which beats that measurement, I will accept the fact that the Amazon River is the longest river in the world.

I saw your video about the longest river and I think you have some non correct information. The source of Amazon river was discovered by czech scientist Bohumir Jánský in 2000 and his team also determined the length of the river at 7062 km.

Interesting that you mentioned adding the Missouri to the Mississippi. However, you failed to mention that the Missouri is presently longer than the Mississippi. Every time an ox-bow curve cuts through or flood waters change the delta, they flip-flop. They are that close in length.

I would use extremely large , "to scale" maps and star laying out a string to trace the path. then measure the string.

Great video as usual! Minnesotan here - just for the record, the local pronunciation for Itasca is eye-TAS-ka!

"It's not about how long it is, it's about what's inside that counts" - Pinnochio

I never knew measuring Rivers was so complicated

A more accurate approach can be sailing a boat down the river (the defined main stream) and measuring its length by the traving speed and duration of the sailing

I found it funny/interesting to hear the pronunciation of "Itasca", the origins of the Mississippi River, simply because I know what it is and never heard it used in this way before. In the video he pronounces it like "it-uh-skuh" when it really is pronounced as "eye-task-ah".

As a former brazillian, gotta say that that way pur scientists used to measure the river was by far the most brazillian thing I've ever seen

As an American, I welcome the new measuring unit of "Frances Per river basin."

The world needs to come to a consensus of what length of measurement should be used to measure coastlines and rivers. 5 to 10km should probably suffice

There’s some incorrect statements in this video. Wouldn't cause the rivers length to be infinity by using a small unit of measurement assuming the middle. The real way to measure a rivers length accurately is to take a boat and drive approximately in middle recording the distance the entire way and that would be the length..

We should embrace a standard method of deducing the length, for example using another specific length , such as the smallest/largest/average width as the segment length f.e. Or, just always use 1 meter or smth.

I don't care of the Amazon or the Nile only the Loire river will stay in my heart as my beautiful one ♥

As a Minnesota native, the way he pronounced "Itasca" broke my soul.

The history channel probably spent more time talking about that aliens created the Nile then how long it is on their homepage...

You do not get the fractal length problem when measuring rivers. If you measure specifically the mid point of the river, smaller measurement units do not increase the length

There's also inaccuracy as far as meanders and islands go and there are probably tens of thousands of meanders and islands on the Amazon. You must use a smaller measure of unit and have an AI apply it to a very detailed satellite image to better estimate its length.

I believe the length of rivers/coastlines converges to an unknown real number rather than diverging as the measurement unit length -> infinity.

I find the whole obsession with river length a bit misguided to begin with. There are many ways to judge the importance of a river, for instance culturally speaking the Nile is certainly more important than the Amazon. But when we talk about "physical features" the Amazon is the king of all rivers and it's not even close. The Amazon carries more water than the next 7 largest rivers *combined*. It's a whole different beast than any other river on this planet. Maybe some other river is technically a little longer, but really that's insignificant. The Amazon truly stands alone, just like Lake Baikal does as far as sweet-water lakes are concerned.

Its called the shoreline paradox where lowering or increasing the measerament unit greatly changes the outcome

I worked for a mapping company in Colorado and we would digitize features like rivers by drawing a line down the center of the river and then boom we would get a measurement

Yes it is possible to measure the length of a river you would just get in a boat where the river begins and float to where the River ends. It's this videos makes something that can be practically measured into some strange mathematical task for no reason. And no matter how you measure it it's not going to be infinitely long.

Which is the river, and which is the tributary, is somewhat arbitrary to begin with. When I look at where the Ohio joins the Mississippi from a satellite view, it looks to me like the "main" river is the Ohio and the Mississippi is feeding into it but the cartographers of history marked it the other way around.

As a Minnesotan, it is pronounced (I-task-a) not (it-is-ca), love the videos.

I love the smooth transition to the sponsor info, well done 👍

1. They say the nile used to run from east to west.
2. Comparing them by volume would be the only way to see which one is superior.

length doesn't have the same fractally unbounded problem as the shoreline perimeter problem.
Let there be a river of arbitrary length and shape with a defined starting point and a defined ending point.
There is a minimum length path that can be drawn between the points, staying within the bounds of the riverbanks, such that no other path can be shorter than it, even with an infinitesimal rule.
Up your math game bruh!