As a boy in Lima, my grandfather told me a legend of the Spanish conquest of Peru. Atahualpa, emperor of the Inca, had been captured and killed. Pizarro and his conquistadors had grown rich, and tales of their conquest and glory had reached Spain and was bringing new waves of Spaniards, hungry for gold and glory. They would go into towns and ask the Inca, "Where's another civilization we can conquer? Where's more gold?"

And the Inca, out of vengeance, told them, "Go to the Amazon. You'll find all the gold you want there. In fact, there is a city called Paititi -- El Dorado in Spanish -- made entirely of gold."

The Spanish set off into the jungle, but the few that return come back with stories, stories of powerful shamans, of warriors with poisoned arrows, of trees so tall they blotted out the sun, spiders that ate birds, snakes that swallowed men whole and a river that boiled.

All this became a childhood memory.And years passed. I'm working on my PhD at SMU, trying to understand Peru's geothermal energy potential, when I remember this legend, and I began asking that question. Could the boiling river exist?

I asked colleagues from universities, the government, oil, gas and mining companies, and the answer was a unanimous no. And this makes sense. You see, boiling rivers do exist in the world, but they're generally associated with volcanoes. You need a powerful heat source to produce such a large geothermal manifestation. And as you can see from the red dots here, which are volcanoes, we don't have volcanoes in the Amazon, nor in most of Peru. So it follows: We should not expect to see a boiling river.

Telling this same story at a family dinner,my aunt tells me, "But no, Andrés, I've been there. I've swum in that river."

Then my uncle jumps in."No, Andrés, she's not kidding. You see, you can only swim in it after a very heavy rain, and it's protected by a powerful shaman. Your aunt, she's friends with his wife."

You know, despite all my scientific skepticism, I found myself hiking into the jungle, guided by my aunt, over 700 kilometers away from the nearest volcanic center, and well, honestly, mentally preparing myself to behold the legendary "warm stream of the Amazon."

But then ...I heard something, a low surge that got louder and louder as we came closer. It sounded like ocean waves constantly crashing, and as we got closer, I saw smoke, vapor, coming up through the trees. And then, I saw this.

I immediately grabbed for my thermometer, and the average temperatures in the river were 86 degrees C. This is not quite the 100-degree C boiling but definitely close enough. The river flowed hot and fast. I followed it upriver and was led by, actually, the shaman's apprentice to the most sacred site on the river. And this is what's bizarre -- It starts off as a cold stream. And here, at this site, is the home of the Yacumama, mother of the waters, a giant serpent spirit who births hot and cold water. And here we find a hot spring, mixing with cold stream water underneath her protective motherly jaws and thus bringing their legends to life.

The next morning, I woke up and -- I asked for tea.I was handed a mug, a tea bag and, well, pointed towards the river. To my surprise, the water was clean and had a pleasant taste, which is a little weird for geothermal systems.

What was amazing is that the locals had always known about this place, and that I was by no means the first outsider to see it. It was just part of their everyday life. They drink its water. They take in its vapor. They cook with it, clean with it, even make their medicines with it.

I met the shaman, and he seemed like an extension of the river and his jungle. He asked for my intentions and listened carefully. Then, to my tremendous relief -- I was freaking out, to be honest with you -- a smile began to snake across his face, and he just laughed.

I had received the shaman's blessing to study the river, on the condition that after I take the water samples and analyze them in my lab, wherever I was in the world, that I pour the waters back into the ground so that, as the shaman said, the waters could find their way back home.

I've been back every year since that first visit in 2011, and the fieldwork has been exhilarating, demanding and at times dangerous. One story was even featured in National Geographic Magazine. I was trapped on a small rock about the size of a sheet of paper in sandals and board shorts, in between an 80 degree C river and a hot spring that, well, looked like this, close to boiling. And on top of that, it was Amazon rain forest. Pshh, pouring rain, couldn't see a thing. The temperature differential made it all white. It was a whiteout. Intense.

Now, after years of work, I'll soon be submitting my geophysical and geochemical studies for publication. And I'd like to share, today, with all of you here, on the TED stage, for the first time, some of these discoveries.

Well, first off, it's not a legend. Surprise!

When I first started the research, the satellite imagery was too low-resolution to be meaningful. There were just no good maps. Thanks to the support of the Google Earth team, I now have this. Not only that, the indigenous name of the river, Shanay-timpishka, "boiled with the heat of the sun," indicating that I'm not the first to wonder why the river boils, and showing that humanity has always sought to explain the world around us.

So why does the river boil?

It actually took me three years to get that footage.

Fault-fed hot springs. As we have hot blood running through our veins and arteries, so, too, the earth has hot water running through its cracks and faults. Where these arteries come to the surface, these earth arteries, we'll get geothermal manifestations: fumaroles, hot springs and in our case, the boiling river.

What's truly incredible, though, is the scale of this place. Next time you cross the road, think about this. The river flows wider than a two-lane road along most of its path. It flows hot for 6.24 kilometers. Truly impressive. There are thermal pools larger than this TED stage, and that waterfall that you see there is six meters tall -- and all with near-boiling water.

We mapped the temperatures along the river, and this was by far the most demanding part of the fieldwork. And the results were just awesome. Sorry -- the geoscientist in me coming out. And it showed this amazing trend. You see, the river starts off cold. It then heats up, cools back down, heats up, cools back down, heats up again, and then has this beautiful decay curve until it smashes into this cold river.

Now, I understand not all of you are geothermal scientists, so to put it in more everyday terms: Everyone loves coffee. Yes? Good. Your regular cup of coffee, 54 degrees C, an extra-hot one, well, 60. So, put in coffee shop terms, the boiling river plots like this. There you have your hot coffee. Here you have your extra-hot coffee, and you can see that there's a bit point there where the river is still hotter than even the extra-hot coffee. And these are average water temperatures. We took these in the dry season to ensure the purest geothermal temperatures.

But there's a magic number here that's not being shown, and that number is 47 degrees C, because that's where things start to hurt, and I know this from very personal experience. Above that temperature, you don't want to get in that water. You need to be careful. It can be deadly.

I've seen all sorts of animals fall in, and what's shocking to me, is the process is pretty much the same. So they fall in and the first thing to go are the eyes. Eyes, apparently, cook very quickly. They turn this milky-white color. The stream is carrying them. They're trying to swim out, but their meat is cooking on the bone because it's so hot. So they're losing power, losing power, until finally they get to a point where hot water goes into their mouths and they cook from the inside out.

A bit sadistic, aren't we? Jeez. Leave them marinating for a little longer. What's, again, amazing are these temperatures. They're similar to things that I've seen on volcanoes all over the world and even super-volcanoes like Yellowstone.

But here's the thing: the data is showing that the boiling river exists independent of volcanism. It's neither magmatic or volcanic in origin, and again, over 700 kilometers away from the nearest volcanic center.

How can a boiling river exist like this? I've asked geothermal experts and volcanologists for years, and I'm still unable to find another non-volcanic geothermal system of this magnitude. It's unique. It's special on a global scale. So, still -- how does it work? Where do we get this heat? There's still more research to be done to better constrain the problem and better understand the system, but from what the data is telling us now, it looks to be the result of a large hydrothermal system.

Basically, it works like this: So, the deeper you go into the earth, the hotter it gets. We refer to this as the geothermal gradient. The waters could be coming from as far away as glaciers in the Andes, then seeping down deep into the earth and coming out to form the boiling river after getting heated up from the geothermal gradient, all due to this unique geologic setting.

Now, we found that in and around the river -- this is working with colleagues from National Geographic, Dr. Spencer Wells, and Dr. Jon Eisen from UC Davis -- we genetically sequenced the extremophile lifeforms living in and around the river, and have found new lifeforms, unique species living in the boiling river.

But again, despite all of these studies, all of these discoveries and the legends, a question remains: What is the significance of the boiling river? What is the significance of this stationary cloud that always hovers over this patch of jungle? And what is the significance of a detail in a childhood legend?

To the shaman and his community, it's a sacred site. To me, as a geoscientist, it's a unique geothermal phenomenon. But to the illegal loggers and cattle farmers, it's just another resource to exploit. And to the Peruvian government, it's just another stretch of unprotected land ready for development.

My goal is to ensure that whoever controls this land understands the boiling river's uniqueness and significance. Because that's the question, one of significance. And the thing there is, we define significance. It's us. We have that power. We are the ones who draw that line between the sacred and the trivial. And in this age, where everything seems mapped, measured and studied, in this age of information, I remind you all that discoveries are not just made in the black void of the unknown but in the white noise of overwhelming data.

There remains so much to explore. We live in an incredible world. So go out. Be curious. Because we do live in a world where shamans still sing to the spirits of the jungle, where rivers do boil and where legends do come to life.

Thank you very much.

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