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Andrés Ruzo was a child when he first heard the story of a mythical river buried deep in the bowels of the Peruvian Amazon, so hot that it boiled. He never forgot about it.

Later in life, as a Ph.D. candidate in geophysics at Southern Methodist University, he set out to discover if there was any truth in the story grandpa once told him.

As a child, Andres loved the story his grandfather would tell of the legions of Spanish conquistadors who headed to the Amazon rainforest in search of gold in the 16th century. The few who returned, the story went, told tales of surviving fatal snakes, warriors with poisoned arrows, man-eating spiders, and a river with temperatures that varied between warm and extremely hot -- way over the boiling point.

Ruzo, who grew up in Perú, decided to base his Ph.D. thesis project on creating the first detailed geothermal map of the Peruvian Amazon — and maybe even finding the fabled stream. His colleagues scoffed at the idea of a boiling river, reasoning that no volcanos existed in the region.

In the Ruzo family, however, the story persisted. "Over a family dinner one night, my aunt, who did work with indigenous human rights, told me that she'd not only heard of the river, but she'd gone swimming in it as a child,” Ruzo told Fox News Latino.

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“She told me that the river was protected by a shaman and healer called Maestro Juan Flores,” Ruzo added, “and that she was friends with the shaman’s wife.”

In a hot steamy day in 2010 Ruzo finally hiked to the forest with this aunt, never believing he'd actually see the river. It took them approximately four hours to get there from the nearest town.

Through the rising vapors it appeared, in all its boiling splendor. Ruzo had come across the sacred geothermal heating site called Mayantuyacu, watched over indeed by the shaman his aunt had told him about. The first thing he did was dip in his thermometer: 187 degrees Fahrenheit.

“It’s very dangerous,” Ruzo said. “If you fell into the river you really would literally boil alive. Not a good way to go.”

It would take Ruzo until 2013 to prove that the river was natural, and not the result of human activity related to oil-drilling activity or a gas mining mishap.

The river, 82 feet wide and 15 feet deep, runs for nearly four miles at temperatures hot enough to boil a chicken for a nice chicken soup.

"The first day I spent at the river, I asked the shaman's apprentice if I could have some tea. The guy handed me a mug, and pointed me to the river," Ruzo said.

As to why on earth the river boils, Ruzo explained in a 2014 lecture that “as we have hot blood running through our veins and arteries, so, too, the Earth has hot water running through its cracks and faults."

Mayantuyacu is not such a secret as it was all through the mid-20th century. Andres acquired legal permission from closed archives to access proprietary to find a collection of confidential reports from the 1930s by American geologist Robert B. Moran, who described his encounter with the boiling river and expressed relief the "Agua Caliente Dome" was not a volcanic structure, as geothermal systems can “overcook” oil reserves, making them worthless.

Today, once a year, a small group of tourists makes the trek into the forest to experience the customary practices of the Ashaninka people.

Ruzo travels to the area often and, with the blessing of the river’s shaman, conducts detailed geothermal studies of the boiling river, attempting to place it in the context of the Amazon basin. He’s also collaborating with microbial ecologists from South America, the U.S. and Canada to investigate the organisms living in the river’s blistering waters. Anything able to survive here could offer insight into how life began billions of years ago.

"When I say the river is sacred,” Ruzo said, “to the indigenous people the spirits and the river are considered a place of union for the spirit and human world."

Sadly, the Peruvian government leaves the land largely unprotected and ripe for development and since 2011 the river’s surrounding forest has been devastated by illegal logging and cattle farmers.

Ruzo said that when he first traveled to the river in 2010 he had to take a two-hour car ride from Pucallpa (the largest city in the central Peruvian Amazon), followed by a 30-minute motorized canoe ride, and lastly an hour-long hike through the jungle.

By May 2014, deforestation had advanced so far into the jungle that the trip from Pucallpa to the river was made door-to-river in three hours by car.

"We want to help. Deforestation is progressing quickly. If they deforest there, the river will continue to flow, but the trees hold the soil, and without the trees soil flows into the water and changes the chemistry of the entire area," Ruzo told FNL.

Ruzo recently received a grant from National Geographic to pay for technology such as drones and satellites to learn which forests are most imminently in danger in the area. He’s collaborating with local leaders in an attempt to stop the deforestation and protect the river.

Shaman Juan Flores gave permission to Ruzo to study the river with the condition that whatever water is removed from the river will be poured out into dirt, so that it may eventually find its way back to the sacred waterway.

The deforestation would impact not only the river, but the people who live alongside it.

Ruzo’s following anecdote illustrates it well:

"Once we were making our way through a particularly dense part of the jungle along the river when our group came upon a wasps nest. The swarm chased us and stung one of my colleagues very badly. The shaman was able to go into the jungle, collect some local plants and create a powerful salve for his stings. I mean this guy was in trouble and we're at least three hours from a hospital," Ruzo said.

Ruzo is the author of "The Boiling River: Adventure and Discovery in the Amazon." The book is published by TED Books/Simon & Schuster. A portion of the proceeds from the book go to the preservation of the river.