This river in Peru is so hot it boils animals alive

Ruzo sampling 207 degree water boiling river
Devlin Gandy

Deep in the heart of the Peruvian Amazon, an anomalous and perplexing natural wonder lies: A raging river that boils.

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Once just the stuff of folklore, geophysicist Adrés Ruzo, a PhD student at Southern Methodist University, set out to find the legendary waterway himself.

He not only found it, but he confirmed that it does, in fact, surge at a scalding 200 degrees Fahrenheit.

"It feels like I'm in a sauna inside a toaster oven," Ruzo said sitting on the bank of the river in his new book, The Boiling River: Adventure and Discovery in the Amazon. (Ruzo also discussed his quest to understand its puzzling features in a recent TED talk.)

While the temperatures are consistent with those of many other natural volcanic and nonvolcanic geothermal systems, the sheer volume of water in the river is perplexing. Without a powerful heat source, such as an active volcano, the river shouldn't boil this hot and high.

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Here's the story of the boiling river, which rages in a forested region called Mayantuyacu.

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Mayantuyacu lies in the central Peruvian Amazon, about four hours by car, motorized canoe, and foot from the eastern city of Pucallpa.

pucallpa map
Google Maps

The river stretches four miles long and can plunge as deep as six feet in spots, and up to 80 feet wide in others. The water surges wider than a two-lane road.

Racing the Night
Devlin Gandy
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Geophysicist Adrés Ruzo measured temperatures at a scalding 186 F, not quite boiling but hotter than a typical cup of coffee.

The Sacred Waters
Devlin Gandy

Water becomes painful and dangerous at around 117 F. "Dipping my hand into the river would give me third-degree burns in less than half a second," Ruzo said in The Boiling River. "Falling in could easily kill me."

Ruzo sampling 207 degree water boiling river
Devlin Gandy
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Fatefully, this frog made the grave mistake of hopping in. Its muscles are literally cooked on the bone.

dead frog in boiling river peru
Andrés Ruzo

The water is so hot locals even use it to brew tea with it.

Hot tea
Rebecca Siegel/Flickr
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Boiling rivers exist in the world, but they're usually attached to an active volcano or a magmatic system, such as this pool off the Boiling River Trail in Yellowstone National Park.

geothermal pool in Yellowstone National Park
Don Graham/Flickr

But this river, which lies 400 miles from the nearest volcano, is an anomaly. Locals believe the river has healing powers. They harness its mysterious energy for traditional medicine.

The Boiling River
Sofía Ruzo
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They say that the medicine in the river's iconic "guardian tree," a Came Renaco, is made more powerful by the river's vapors.

El Came Ranaco
Sofía Ruzo

Nobody knows why the river runs so hot. One hypothesis is that it was the result of an oilfield accident, but Spanish conquistadors allegedly encountered it hundreds of years ago.

Post apocalyptic Amazonia
Andrés Ruzo

Source: Science Alert/TED

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Ruzo's best working hypothesis is that hot geothermal water is pouring in from fault zones, cracks in the earth, heating up the river's temperature and volume.

Andres with thermal camera
Sofía Ruzo

Whatever it is will take years of dedicated field work and collaboration with the locals to understand its true origins. Until then, it continues to mystify scientists, historians, and locals alike.

Andres at Mayantuyacu's border
Guida Gastelumendi
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