How I Found a Mythical Boiling River in the Amazon

The trees are so tall, and the jungle so thick, that it is difficult to distinguish the topography above the ridge. In places, thatched-roof homesteads sit on lush lawns dotted with large trees and grazing cattle. These patches of domesticated jungle expose rolling hills and ravines.

“Isn’t it incredible?” Guida says, beaming. “I love the jungle.”

“It’s beautiful.” I nod. “But I just can’t wait to see this thermal river. Honestly, I’m having trouble focusing on much else.”

Guida laughs. “Try to enjoy the present a little more,” she says. “The river will come soon enough.”

We hear a shout from the front of the pekepeke, where our second guide, Brunswick, is standing. He is in his early thirties and is Maestro’s apprentice. “Look over there!” he says, pointing some thirty feet ahead. “There is the mouth of the Boiling River where the hot and cold waters meet.”

Finally, the river! My eyes scan the scene. A tributary to our right, wider than a two-lane road, is injecting a significant quantity of flow into the Pachitea. Where the two waters collide, a dusky olive-green plume of water curves into the Pachitea’s chocolate brown. But I don’t see even the slightest wisp of steam.

The prow enters the plume and Brunswick dips his hand into the green water, signaling to me to do the same.

I dip my hand into the cold brown water of the Pachitea. The moment we pass into the green plume, the water becomes warm. It gets warmer and warmer as we near the tributary, until finally we glide into its mouth. Here the water is significantly warmer, like hot bathwater — but nowhere near boiling.

I shouldn’t feel disappointed, but my excitement has gotten the better of me. This “Warm River of the Amazon,” is not the stuff of my dreams. The “Boiling River” has not lived up to its name. I let out a deep sigh.

Okay, no more speculation, no more expectations. I need to get to Mayantuyacu and let the river tell its own story. Focus on real quantifiable data, not hearsay.

Expertly navigating the pekepeke, Francisco steers the boat to shore, where steps carved into the cliff’s reddish mud beckon us toward the next leg of our journey.

I turn on the path tracker on my GPS and slip it back into my backpack.

Disembarking, we climb to the top of the bank, where we see a thin, muddy trail entering the forest. Francisco pushes off and heads back to Honoria as Brunswick leads us into the jungle.

The trail is well trodden but uneven. Massive trees with imposing buttress roots shade us from the hot sun. Twisting vines with bizarre forms and textures snake through the foliage. Electric-colored flowers hang above us, so delicate and exotic that I find it hard to believe they are natural. As we hike up and down the undulating topography, hidden animals serenade us. Squadrons of mosquitos stalk us. Our liberally applied insect repelled forms a forcefield where a blanket of mosquitos hovers, just out of reach.

At the end of a large clearing, near the crest of a tall ridge, I notice a heavily eroded dirt road. I ask Brunswick about it.

“Loggers came through here many years ago in tractors and took away the big trees,” he answers solemnly. “They were chased out, but the clearing remains.”

Guida speaks in a pained tone. “Many years ago, I was doing social work with an indigenous group in the jungles far south of here. I was staying in a village on a large river, and though the area was supposedly protected, the locals were still having problems with illegal loggers. One night I couldn’t sleep, so I took a walk to the river. When I got down to the bank, I heard strange noises. The full moon let me see clearly, though a part of me wishes I hadn’t looked. From end to end, as far as I could see upstream and downstream, the river was full of massive lupuna trees. Men with long poles walked back and forth across the giant floating logs, guiding them downstream. It was clear why they were transporting the trunks at night.

“Each of those trees was easily hundreds of years old. This was exactly what I was helping the community to fight. I felt so hopeless, and I knelt down and wept.

“The next day, I relayed what I had seen. The villagers were all too familiar with this sort of scene. They described how the loggers would appear, cut down the big trees, then clear-cut and burn swaths of land to form paths to roll or drag the trunks to the nearest river, using tractors like the one that left the trail we just saw.”

A wave of anger washes over me. “That’s terrible,” I mutter.

“But the worst part came later,” Guida continues. “We discovered that most of those ancient trees were being used to make plywood. Plywood! The lupuna is known as the Lady of the Jungle. Their trunks can be more than three yards wide.”

“They are thought to contain powerful spirits, and in some tribes it is considered a grave offense even to relieve oneself near one. And they are being used for plywood.”

A depressed silence envelops our small group as we continue our journey through the jungle. My thoughts shift back to the Boiling River. If accounts of the river are true and not merely an exaggeration, there are three possible explanations: it’s a volcanic/magmatic system, it’s a nonvolcanic hydrothermal system where geothermal waters are quickly being brought to the surface from deep within the earth, or it’s man-made.

This last possibility is disconcerting. What if the Boiling River is just the result of an oilfield accident — an improperly abandoned oil well, a frack job gone wrong, or oil field waters improperly re-injected into the earth? I know of many cases, in Peru and abroad, where oilfield accidents have caused geothermal features — the most infamous being the Lusi mud volcano in East Java, which has displaced more than thirty thousand people. Accidents of this scale quickly take on significant financial and political importance, and as a result, Lusi’s “true cause” remains a contentious issue. In the Talara Desert, I recently visited two tourist attractions with surprising backgrounds. The plan had been for two old oil wells — wells that were only producing warm, salty water — to be properly sealed and closed up by the oil companies. As the story goes, the locals saw potential in the pools of warm water and pressured the companies to keep the wells open. The oil companies gave in, and the wells were converted into bathing pools. Now unsuspecting tourists pay to relax in the “natural healing thermal waters” while rubbing the “rejuvenating” thermal muds on their faces. I let out a long exhale as I realize that this horrible possibility might be the most likely explanation.

We are near the oldest oilfield in the Peruvian Amazon — it’s a well-studied area, and a large thermal river isn’t exactly easy to miss. Furthermore, the river doesn’t appear on the Peruvian government’s geothermal feature map — though that 1965 report mentions a “small, warm spring” somewhere in this general area . . .

Maybe the river was a small, warm spring that accidentally became a boiling river. Maybe the legends came later — I’ve seen it happen in other parts of Peru. Maybe I’m walking into an oil field cover-up. Accidents are bad for business, after all, and companies paying off government officials to ignore such “minor inconveniences” are hardly unheard of.

Frustrated, I shake my head to try to clear my mind. I’m so sick of all these uncertainties, I think. Until I see real data I know nothing. I need a solid GPS location to determine exactly how close the river is to the nearest oilfield. I need precise temperature data to figure out how exaggerated these accounts are. Most important, I need to find that stupid 1933 Moran study — it’s the only study done before this area was developed, and the only one left that could mention the river.

I prepare myself to accept whatever outcome I find. Science is not about the story we want to hear––it’s about the story the data tell us.

Just then Brunswick stops and points out a thick metal pipe, partially buried, running across the trail. “This oil pipeline once went from the oilfield to Pucallpa,” he says. “They stopped using it years ago and most of it has been stolen now.

It marks our property boundary — from here to the river, we are in Mayantuyacu.”

A large painted wooden sign reads: mayantuyacu — zona prohibida.

“Prohibited zone?” I turn to Brunswick. “Prohibited to whom?”

“Loggers, hunters, squatters. We are trying to do good work in Mayantuyacu — healing people and giving them traditional natural medicines. We get our knowledge from the plants and the grandparents.” He pauses, looking up at a large, thick tree.

Brunswick gently places his hand on the tree trunk. “The spirits leave when the land is cleared.”

Pointing to the sign, he adds: “Mayantu for the spirit of the jungle, and Yacu for the spirit of the water. Here we heal by working together with both spirits.”

His words, spoken with profound respect, strike a chord in me. I resolve to keep my hypotheses to myself — even healthy scientific skepticism about the river could be misinterpreted as disrespect.

We reach the top of a second great ridge crowned by massive trees, guards of the surrounding jungle, and rest a moment, Guida and I taking deep ragged breaths. Our two-hour hike in the heat has taken the energy out of us.

“Almost there,” Brunswick assures us. As our gasps subside, I hear something in the distance. “What’s that sound?” I say. “It’s like a low surge.” Brunswick raises his eyes to me and smiles. “The river.”