23/02/2016 1:53 PM AEDT | Updated 24/02/2016 12:47 AM AEDT

This Incredible 'Boiling River' Is A Scientific Enigma

Hidden deep in the Amazon, this river "is a reminder that there are still great wonders to be discovered."

When geoscientist and National Geographic explorer Andrés Ruzo was growing up in Lima, Peru, his grandfather used to tell him wild stories of Spanish conquistadors, cities of gold, and an Amazonian river so hot it could boil men alive.

But it wasn't until Ruzo was studying geothermal energy that he decided to look into this mythical boiling river -- and, much to his surprise, actually found it. While boiling rivers do exist in the world, they are usually found close to active volcanos. This river is especially remarkable because it runs more than 400 miles from the nearest active volcano -- the only non-volcanic river known to boil on Earth. 

"At a time when everything seems mapped, measured and understood, this river challenges what we think we know," Ruzo writes in his new book, The Boiling River: Adventure and Discovery in the Amazon. "It is a reminder that there are still great wonders to be discovered." 

Located in a forest region called Mayantuyacu, the sacred boiling river, which is guarded by a shaman, flows hot -- between 120 and 196 degrees Fahrenheit -- for almost 4 miles and is about as wide as a two-lane road.

Its ancient name, "Shanay-timpishka," loosely translates to “boiled with the heat of the sun,” Ruzo writes in National Geographic. Locals say it is hot because of the Yacumama, "a giant serpent spirit who gives birth to hot and cold waters and is represented by a large serpent head-shaped boulder at the river’s headwaters."

"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," Ruzo said in a 2014 episode of TED Talks. "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." 

Yet somehow, the natural wonder managed to go relatively unnoticed by the larger world, especially scientists.

Sofia Ruzo
A shaman stands at the edge of the boiling river.

Since first visiting the river in 2011, Ruzo has attempted to understand the phenomenon, returning annually to conduct scientific research

As he explains in his TED Talk, his research shows that the river exists independently of volcanism and is the result of a large hydrothermal system.

"The waters could be coming from as far away as glaciers in the Andes," he said, "then seeping down deep into the Earth and coming out to form the boiling river after getting heated up from that geothermal gradient, all due to this unique geologic setting."

His book announces the discovery of "previously undocumented species of extremophile microorganisms living in and around the Boiling River at temperatures that would kill us." Understanding the organisms, he says, may help scientists understand how life originated on the planet. 

Devlin Gandy
Andrés Ruzo collects a water sample from Peru's boiling river. 

Ruzo has kept his research mostly in the dark for the past five years in order to "introduce the river to the world responsibly." The river, he notes in his book, is not yet legally protected and is not significantly marked on any map. His research forced him to navigate the "tangle of competing interests -- local shamans, illegal cattle farmers and loggers, and oil companies." 

To help protect this rare natural wonder and the surrounding jungle, Ruzo has founded a nonprofit called The Boiling River Project, where he posts more scientific findings.

"Be curious," Ruzo urges readers in his book. "There is significance in the landscapes we pass by, in the pixels of Google Earth's satellite imagery, and in the smallest details of stories." 

See his 2014 TED Talks episode below for more details.