Amazon's legendary boiling river remains mysterious after first scientific study

The awe-inspiring, dangerous and often times mysterious Amazonian rainforest has long captivated scientists and explorers with the possibility for new discoveries, while stirring up myths and legends about the plants, creatures and unique topography found within.

As a child growing up in Peru, Geoscientist and National Geographic Explorer Andrés Ruzo would listen to his grandfather's stories regarding the Spanish conquest of Peru, and how the Inca leaders told the Spaniards that the golden city of El Dorado awaited them inside the lush jungles of the Amazon.

"The Spanish set off into the jungle, but the few that returned came 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," he said during a TED Talks speech, regarding his study of a geologic anomaly, the same legendary boiling river that had once been nothing more than a childhood memory.

In 2011, while working toward his PhD in geophysics at Southern Methodist University and attempting to understand Peru's geothermal energy potential, the memory of the legendary boiling river sparked Ruzo's latest adventure, which followed a dinner conversation with his aunt who had been to the site before.

While the river was new to Ruzo and had never been studied scientifically, the naturally hot water, which boasts average temperatures along a 4-mile stretch of more than 186 F, was a part of everyday life to the local people living near its banks. To the locals, the river is named Shanay-timpishka, which means "boiled with the heat of the sun," according to National Geographic's Adventure Blog.

The boiling waters are also a bit of a geologic anomaly, located more than 400 miles away from a volcanic center, which at first made Ruzo skeptical of its existence as he followed his aunt's guidance to its location, he recalled during his Ted Talk.

"Much of the Andes of Peru have no volcanoes," AccuWeather Meteorologist Jim Andrews said, adding that the site lies east of the "volcanic gap."

"The Boiling River is an anomalously large thermal river. It flows hot for almost 4 miles, is generally about as wide as a two-lane road, but can get up to 80 feet wide at its widest point, and can get to 16 feet deep at its deepest point," according to boilingriver.org, a website hosting Ruzo's "The Boiling River Project," which was created to protect it against developments that would threaten nearby communities, the fragile ecosystem, and the geologic study of the sacred river site.

"Even more impressive, despite the tremendous amount of hot water, it is non-volcanic," Ruzo said. "In fact, the nearest active volcanic center is over 430 miles (over 700 kilometers) away."

"The data is showing that the boiling river exists independent of volcanism. It's neither magmatic or volcanic in origin," Ruzo said, describing the fault-fed hydrothermal system that has created perhaps the largest one of its kind in the world.

"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," Ruzo said.

After years of work studying the river, Ruzo made the decision to delay his PhD defense in order to protect the site from exploitation, according to boilingriver.org.

"His decision was directly influenced by what is best for the river’s conservation, especially in light of multiple solicitations from energy development companies seeking geologic and geothermal data on the Boiling River," the website reports, adding that the site is not only important from a scientific perspective, but is a sacred site of the local people living nearby.

The river may be a result of a large hydrothermal system where waters, possibly coming as far away as glaciers in the Andes, are seeping deep down into the earth, are being heated up from the geothermal gradient and are then released at the site, Ruzo said. "The non-volcanic 'geothermal gradient' is about 25 degrees C/1,000 meters, or 1 degree F/70 feet. If the site of the river has a normal background gradient, this suggests that the water feeding the hot springs must flow from at least 3,000 meters depth, or even lower, allowing for loss of heat to the surroundings on the way up," Andrews said, adding that this is based on the mean yearly temperature, 80 F, of the region.

According to Ruzo, continued research still needs to be conducted to better understand this unique phenomenon.

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