- [Narrator] What's over 4,000 miles long and spans over six countries? No, it's not the world's
largest conga line. It's arguably the most famous
waterway on the planet, the Amazon River. This watery wonder is
believed by many to be the longest river in the world, closely followed by the Nile. Although these two rivers
may share a similar size, there's one thing that they
don't have in common... bridges. In total, the Nile has nine
crossings over Cairo alone, while shorter rivers like
the Yangtze and Danube both have over 100. How many bridges does the Amazon have? A grand total of zero! So, what's the reason behind this? Boiling lava water? Tsunami-like waves? Or maybe even a super-sized
serpent lurking in its depths? Well, get your waders on,
because we're about to uncover the mystery of why the Amazon River has no bridges whatsoever.
(cool music) The first thing you'll
notice about the Amazon River is its sheer size. Stretching some 4,345 miles
long, it's fair to say that this river is lengthy. So lengthy, its course runs
even longer than the distance between Alaska and New Orleans! Being such a big river, it's unsurprising that the Amazon releases a lot
of water into the Atlantic, and I mean a lot! The river distributes around
44,000 gallons of freshwater into the ocean every second. That means in 24 hours, the Amazon spills some 3.8 billion gallons of
freshwater into the Atlantic. For some perspective, that's equivalent to tipping 5,759 Olympic
swimming pools of water into the ocean every single day. Together, this freshwater flow accounts for nearly 20% of all river
water that enters the sea! Okay, so the Amazon River may be long and chock full of water, but that doesn't mean you
can't build a bridge across it, especially if it's narrow. And, during the dry season, the
river isn't impossibly wide, averaging a width of two to six miles. Okay, that might sound
huge, but considering that the Golden Gate
Bridge in San Francisco is 1.7 miles long, building a crossing over the Amazon River
seems feasible at least. That's until the wet season hits. From mid-December to
mid-May, the heavens open over the Amazon. So much so that the water levels
can rise to almost 50 feet, the same height as a five-storey building! But if you think that's a jump, you haven't seen anything yet. During these months,
the width of the river not only deepens, it also swells. In some parts, it can reach
between 24 and 30 miles wide! That means, during the wet
season, if you built a bridge over the Amazon River at its
widest point, it would need to be a colossal 17 times longer than the Golden Gate Bridge! You hear that? That's the sound of engineers around the world weeping in despair. But the effects of the wet season don't stop at wider rivers! Aquatic grasses, known as
matupás, can cluster together on the river's surface. When the flood season
hits, these floating blocks of vegetation become filled with water, before sinking to the riverbed and dying. But, during the dry season, the flora formations rise again literally! Floating on the water's
surface, the vegetation patch provides a substrate of partially
decomposed organic matter, on which plant species can start growing. The cycle of submerging and
floating of the grass blocks repeats itself over the course of successive wet and dry seasons. Over time, matupás can reach
up to around 40 feet tall and grow as large as 10 acres! To put that into context, the size of your average American football field is just over one acre. Yeah, I think it's fair to say that matupás are pretty chunky. Now, that may provide
a welcome resting place for some Amazon wildlife,
but it's far from ideal to have a floating island
bobbing along the river if you're trying to construct a bridge! And yet, it's not just the
wet season that can be blamed for the Amazon River infiltrating
engineer's nightmares. Twice a year, during the biennial
equinox, the Sun and Moon exert a stronger pull on the Earth than the rest of the year. And it's this pull that brings the tides to their highest peaks. In the case of the
Amazon, these huge waves, come crashing in from the Atlantic Ocean, where they overpower the current
at the mouth of the river, reversing its flow in the process. This phenomenon, known as
a tidal bore or a Pororoca, wreaks havoc upon the Amazon. These weighty waves can advance as far as 500 miles upstream,
clocking soaring speeds of 15 miles per hour. That coupled with 13 feet high waves makes for a devastating mix. (heavy waves of water)
(running breathless) You're right to run, my guy! This mega wave will swallow
pretty much anything in its wake. That's not even to mention
the horrors that these waves can bring with them. Whether it's uprooted
trees, massive matupás or even predators, like
piranhas and caimans, let's just say you wouldn't
want to get in the way of a pororoca. Call me crazy, but I'm
not sure how I'd feel about crossing a bridge,
while a tree, an island and a caiman came hurling towards me! Obviously, this river's insane
width, floating matupás, and tidal bores make it
incredibly tricky to bridge over. Tricky, but technically not impossible. After all, you could build
a bridge far enough upstream to prevent tidal bores
splitting the crossing in two. Matupás, annoying as they
may be, aren't prominent throughout the river's course. And regarding the width,
why not just choose one of the narrower sections of the Amazon? However, there's another
factor that really ramps up the difficulty of bridge-building
over this watercourse. Thanks to its dense rainforest, the Amazon has very few roads dissecting through it. And without roads, which are needed to transport essential
construction materials, you can't have bridges! Take Macapá, on the northern
shore of the Amazon delta, for example. It's a city of more than
half a million people. And yet, there's not a
single road connecting it to the rest of Brazil! The only way to reach
Santarem, the next big city to the west of Macapá,
is via plane or ferry. Why? Well, for much of its 4,345-mile length, the Amazon River meanders
through many areas that are sparsely populated, meaning that very few
major roads are needed. And, even when roads are built there, it doesn't always go to plan. In 1973, the BR-319 was opened. This mega-road runs 540
miles long, from Porto Velho in southern Brazil, to
Manaus, a city located right in the heart of the Amazon. But, as you know, nothing
in this place comes easily. Thanks to that trusty wet season, which regularly dumps more
than eight inches of rain per month from December
to May across the region, a 250 mile 'Middle Stretch' has since been transformed
into a muddy swampland. (engine revving hardly)
(speaking hardly) No matter how big your four by four is, there's no way you're making
it down 250 miles of this! However, since 2015, a maintenance program has made it marginally
passable during the dry season. And in July 2022, former Brazilian
President, Jair Bolsonaro went a step further, vowing his support for the complete re-construction
of this 'Middle Stretch' of BR-319. Sounds promising, but...uh...
then there's the delicate subject of the bill. I mean, did you see
the state of that road? Estimated costs total a
dizzying $265 million. But with most construction
projects, it's far likely that the end result will
far exceed this fat figure. Now, that may seem expensive, but we're only getting started! Remember, that's the
cost for the road alone, we've not even got to the
main course yet, the bridge! Back in 2010, Brazil built
a bridge over the Rio Negro, the Amazon's largest tributary. This 2.2-mile chunk of
engineering excellence connects the cities of
Manaus and Iranduba, limiting the busy ferry
traffic across the tributary in the process. Impressive as it sounds, the
Rio Negro Bridge still cost an eye-watering $570 million to build. Presuming that an
Amazonian bridge would cost a similar amount, the total
damage for repairing the BR-319 and bridging over the Amazon
is likely to set Brazil back over $835 million!
Yikes! With such a perilous price tag, there needs to be high-demand
to justify building such a bridge. And, as the Amazon tends to meander through sparsely populated
areas, there just isn't enough of a reason to splash out on
a near-billion-dollar bridge! Instead, most people
have become accustomed to crossing the river by boat or ferry. Well, if it ain't broke, don't fix it! But Rio Negro, isn't just known
for having a fancy bridge. The Encontro das Aguas, otherwise known as the 'Meeting of the Waters' is the place where the Rio Negro and
the Amazon River meet. But the rivers don't technically meet. Instead, there's a clear
divide between the color of the two waters that's so distinct, it can even be seen from space! I mean, that's got to be the
work of some wicked demon, lurking deep within the
Amazon River, right? Well, you'll be glad to know that the 'Meeting of the
Waters' is simply down to the difference in
temperature, speed, and murkiness between the two bodies of water. Phew! I can only give my soul to so many demons! Okay, so the 'Meetings of the Waters' may not pose any threat to
someone crossing this river, but there are a few darker,
more disturbing theories, as to why no single
bridge crosses the Amazon. To explain, let's turn the
clocks back 60 million years, to the Palaeocene epoch. At this time, a deadly
creature lurked in the swamps of Colombia, a country that the
Amazon River passes through. Now, anyone with a fear of
snakes, brace yourselves for this. This prehistoric predator,
known as the Titanoboa, stretched out to around 50
feet long, and weighed in at a stocky 2,500 pounds. For some perspective, green
anacondas take the prize for chunkiest snake today,
but at their biggest, they're only around 1/5th of the weight of the terrifying Titanoboa. Okay, before you freak
out, you'll be glad to know that the Titanoboa is extinct and has been for nearly 58 million years. So, no need to worry about any
super-sized snakes slithering through the waters of the Amazon, right? Right?! Well, somehow, despite
their supposed extinction, there have been multiple
sightings of giant snakes swimming in the murky Amazonian waters! Yep, there's no way you'll
see me crossing here! The first widely known account of an apparent Titanoboa
sighting was by Percy Fawcett, a British geographer and
explorer of South America in the early 20th century,
who wrote about the experience in his diary: "We stepped ashore and approached
the reptile with caution... As far as it was possible to measure, a length of 45 feet lay out of
the water, and 17 feet in it, making a total length of 62 feet." But Fawcett's claim
wasn't taken for anything more than a good story. I mean, it wasn't helped
by the explorer claiming to have seen a dog with two
noses, as well as a giant spider the size of a dinner plate, that left its victims
blackened from its poison. Sounds like Fawcett may have licked one too many Amazonian toads. Well, turns out that
the spider the explorer was describing may have
been the Goliath birdeater, what a name! It's the world's largest
spider, capable of growing to around the size of a
puppy... not quite as cute. And as for the creepy
canine, no other mention of this unusual
double-nosed dog occurred... that was until fellow
explorer, John Blashford-Snell, another great name, encountered a pupper with a double-barrel snoot! Turns out that a rare breed of dog, known as the double-nosed
Andean tiger hound, inhabits the shadowy depths of Bolivia, another region that the
Amazon spreads through. So, if the double-nosed dog
and giant spider turned out to be sightings based on
animals that actually exist, perhaps Fawcett's
sighting of the Titanoboa was real after all? It may sound crazy, but
Fawcett isn't the only one to have spotted a scarily
sized serpent in the Amazon. Yacumama, meaning 'mother
of water', is the name given to a 200-foot-long serpent, believed to dwell in the Amazon River. According to legend from
indigenous Amazonian tribes, this beast would suck up any living thing that passed within 100 steps of it. Yeah, getting vacuumed
up by a bus-sized snake would be reason enough for
me to never even think about crossing a bridge over the Amazon! But, Yacumama's reign
of terror doesn't stop at hoovering up humans... The Shanay-Timpishka is a
tributary of the Amazon River, found in Peru. Although it may look idyllic,
this stretch of water is straight from the pits of hell... well, at least it feels like it. Shanay-Timpishka is known
for its boiling water ranging from 113 to 212°F. And local shamans believe
that the steamy stream was birthed by Yacumama. Is there anything this snake can't do? Hardcore as that sounds,
the more likely explanation is that the tributary is located
above deep-rooted faults, allowing the water to travel deep down into the Earth's crust. Here, it gets heated up by
rocks in close proximity to the superhot Mantle. The fiery water is then fed
back to the Earth's surface through hot springs that
heat up the spicy river. Regardless of how Shanay-Timpishka
originally formed, one thing's for sure, any
bridge built over this place needs to come with
extra-high safety barriers, being boiled alive doesn't
sound like the best way to go. Recent tales of the Titanoboa and Yacumama definitely makes you second
guess whether building a bridge over such a wicked waterway is worth it. But scary as these stories
sound, they're more likely down to inaccurate measurements or mysterious, legendary indigenous tales
that aren't necessarily based on anything real. However, that doesn't
mean that the Amazon River is a peaceful paradise! Whilst the Titanoboa and
Yacumama may not exist, plenty of nightmare-inducing
critters lurk beneath the water's surface. Take the green anaconda, for example. These bulky boys may not
be as big as a Titanoboa, but they can still
reach over 30 feet long. Luckily these snakes aren't venomous, but that certainly doesn't
mean that they're not a danger. The scary serpents use their strong jaws to capture their prey,
before using their thick, muscular bodies to wrap around
their kill to suffocate it. Green anacondas can even detach their jaw to swallow larger prey,
like caimans and tapir! Fortunately, there's not much evidence of these serpents dining
on humans for dinner! However, not all critters
found within the Amazon River are capable of suffocating you to death, but that doesn't make
them any less menacing. The Amazon's full of a variety of freshwater stingray
species that may look cute, but be warned, these guys pack a punch. Although stingray attacks
on humans aren't too common, they've been known to whip their tails at anyone that gets too close. When a stingray whips its
tail against a victim, the spines within the
tail pierce the skin. The pain the barbed stinger
causes is intense, but compared to the venom some freshwater
species inject, it's nothing. Initial symptoms include
red, swelling skin, before the body tissue
around the affected area begins to die. If that wasn't bad enough,
stings can also lead to vomiting, sweating, respiratory
depression, muscle twitching and seizures. In a study from 2020, 27%
of people who were stung by stingrays reported
further complications in the months after the
accident, ranging from numbness, tremors and even amputations
to affected limbs. In Colombia alone, more than
2,000 stingray-related injuries are reported every year.
Ouch! Venomous stingrays, giant
suffocating anacondas, and maybe even a
truck-sized serpent or two. We get the picture; the Amazon River is not to be messed with. But the horrors don't end there. Now, many of you may think
catfish are pretty harmless... the wet variety, that is. Not the ones hiding behind
well-endowed avatars who're after your credit card details! No... meet the piraiba, the
largest catfish in the Amazon. (3 man speaks in foreign language) This frightening fish
measures over 10 feet long and weighs around 330 pounds,
that's almost double the size and weight of a typical adult man! But size isn't the only
freaky feature of the piraiba. They're generally
considered pretty harmless, feasting primarily on
a diet of other fish. That being said, their stomach contents have been found or
include parts of monkeys. Eugh! Think that sounds rough? Well, there's even been
talk that these catfish have an appetite for
(gulps cutely) human flesh! Back in 1981, the Sobral Santos
II, a ferry which operated on the Amazon, capsized,
and sank in the river. Around 500 people were on
board, yet only 178 survived. So, what happened to the
hundreds of other passengers? Well, it's believed that hordes
of piraiba were responsible for pulling struggling
victims down under the water! When the ship was retrieved
from the riverbed, a shocking discovery was
made: Bodies were found, but they had huge chunks of flesh missing. Man, piraiba don't mess around! All of a sudden, crossing the Amazon sounds like a death wish. Today, ferries and boats are at hand if we need to cross the Amazon River... not that that's always saved humans! But back in the day, there
wouldn't have been such luxuries to help people travel along the river. After all, indigenous groups have lived throughout the Amazon for
at least 11,200 years, long before advanced technology created motorized water transport. Researchers have long
assumed that the land surrounding the Amazon River
didn't become densely populated until after the arrival
of Spanish colonizers in the late 15th century. The belief was that before the arrival of these foreign explorers, the Amazon was home to small nomadic
tribes who left the rainforest in pristine condition. However, recent technological developments have discovered evidence
that blows this assumption out of the water. Lidar, in particular, has
been incredibly useful; utilizing a remote sensor,
it uses laser beams to pass between the leaves and
branches of the trees, bouncing back to provide
a 3D image of the ground below the thick canopy. It revealed that ancient
Amazonians built and lived in densely populated centers. These communities featured
monumental mounds, 65 feet-high pyramids, raised
fields for agriculture, and almost 600 miles of
canals and causeways, which were used to connect forest islands. The researchers also theorized
that population densities were much larger than they first thought. Previously, it was believed
that about 2 million people lived in the entire Amazon basin. However, it's now believed
that between 500,000 and 1 million people once
lived in just 7% of the area! Clearly, the Amazon was much more advanced than anyone could've imagined. And, considering that indigenous tribes were capable of building
causeways and canals, who's to say that there
weren't once ancient bridges crossing the Amazon River,
that've since been lost to the Amazon jungle? After all, bridges
wouldn't be the first thing to be swallowed up by
the great green giant that is the Amazon. You may know it better from the film, but the "Lost City of Z" is believed to have been a real city that existed in the Mato Grosso region of Brazil. Remember our boy Percy Fawcett? When he wasn't out spotting hell snakes, he was obsessed with finding
this mysterious civilization. During his trips to South
America, Fawcett became infatuated with stories of a city that
lay deep within the Amazon. He'd heard tales from
the native tribespeople, and later read similar
accounts by European colonizers who mentioned that they saw
"ruins of size and grandeur which must have been there,
and how populous and opulent it had been in the age when it flourished". So, in April 1925, he
set off with his son Jack and Jack's best friend, Raleigh Rimmel. But Fawcett wasn't able
to find the Lost City. Ironically, he's never been found either. His last known letter was
written on 29th of May 1925 at a location called Dead
Horse Camp, which stated the group's plan to head
into unexplored territory. Sadly, Fawcett and co were
never heard or seen again. No one knows for sure what
caused the demise of the group. Some have speculated that
local indigenous people were to blame. Others believe that they
were struck down by fever, or perhaps they became lost
and succumbed to starvation. While it's unlikely that
Fawcett ever discovered the Lost City of Z, his expedition certainly ramped up interested
in the curious civilization. Recently, an anthropologist
called Michael Heckenberger, with the help of the local
Kuikuro people of Mato Grosso, uncovered an ancient
civilization called Kuhikugu. Considering it was located 140 miles from the last place Fawcett
was known to be alive, Dead Horse Camp, it's certainly possible that Kuhikugu was the 'Lost City of Z' that Fawcett was looking for. It's believed to have been
inhabited from the year 500 until as recently as 1615, and
included 20 towns in an area that spread around 7,700 square miles. Close to 50,000 people
may have once lived here! For some context, that was
around the same population of London in 1500! But size isn't the only
impressive thing about Kuhikugu. According to Heckenberger, the engineering of this civilization was
advanced enough to build moats, along with bridges that crossed
large sections of river. Bingo! So, the Amazon River, in history at least, might once have had a bridge! Ah, but remember, nothing
with this place comes easy. The site of Kuhikugu is
located in Mato Grasso, which is south of the Amazon River. The closest water source
to this civilization would've instead been the Xingu River, a southerly tributary of the Amazon. Ah man, and to think
we'd almost cracked it! But, even if the people of
Kuhikugu never built a bridge to cross the Amazon, all hope is not lost. Thanks to the introduction
of lidar technology, as well as the regrettable
deforestation of the rainforest, researchers are constantly
getting a clearer picture of the ruins left behind by
ancient Amazonian civilizations. Who knows, it may just be a matter of time before an ancient
bridge-building civilization, like the one at Kuhikugu, is found on the banks of the Amazon River! There is one teeny tiny problem, however. If the Amazon was home to
such advanced societies, what could've possibly happened
to all of the civilizations and the structures that they once built? They couldn't have just vanished! Maybe Yacumama swallowed them up? Luckily that wasn't the case, but the true story isn't
much more cheerful. In 1541, Francisco de
Orellana sailed the length of the Amazon River, becoming
the first European to do so. That led the way for many
more explorers to delve into the mysterious marvel
in the coming years. But Europeans weren't
the only thing to arrive on the shores of the Amazon. With them, they brought diseases
like smallpox and measles. Because the untouched tribes
of the Amazon had never come into contact with these illnesses, they had no immunity to them. As a result of exposure
to foreign diseases, and the notoriously brutal
treatment from colonizers, Amazonian population was reduced by 90% within just 100 years of
the arrival of Europeans. But even if the people
were virtually wiped out, that still doesn't explain
why advanced technologies, like lidar, are needed
to discover settlements. After all, ancient civilizations
in places like Greece, Egypt and Mexico have ruins
from thousands of years ago that are still standing today! So, why doesn't the Amazon
have its own acropolis or stone pyramid? Well, unlike the stone
structure of those ruins, the Amazon's indigenous
people built with wood and earth. They're obvious building
materials, given their abundance in the rainforest. Unfortunately, though, wood
decays if it's not maintained. And as a result,
potentially countless bridge ruins from bygone Amazonian civilizations seem to have been
swallowed up by the jungle! Man, much like the Amazon River, that's something I don't
think I'll ever get over. With all that said, what do
you think is the biggest reason for why there are no bridges
over the Amazon River? And would you be brave
enough to cross the river if a bridge was built? Let me know in the comments down below, and thanks for watching!
(slow upbeat music)
