Scientists found a mysterious ‘boiling’ river straight out of Amazonian legend

Science Alert
For centuries, Peruvian locals have talked about a river in the Amazon that burns so hot it can kill.
According to legend, Spanish conquistadors foolishly ventured into the rainforest in search of gold, and the few men that returned told stories of poisoned water, man-eating snakes, and a river that boiled from below.
For Peruvian geoscientist, Andrés Ruzo, the myth had fascinated him since childhood.
But it wasn’t until he was completing his PhD project on geothermal energy potential in Peru that he began to question whether the river could actually be real.
According to the experts he spoke to, the answer was a unanimous “no” – after all, hot rivers do exist, but they’re generally associated with volcanoes, and there are no volcanoes in that part of the country.
But when Ruzo went home over the holidays and asked his family where the myth had come from, his mother told him that the river didn’t just exist, she and his aunt had actually swum in it before.
It sounded pretty ridiculous, but in 2011, Ruzo took a chance and hiked into the Amazon rainforest with his aunt, and saw the famed river with his own eyes.
Much to his disbelief, it was steaming hot.
“When I saw this, I immediately grabbed for my thermometer,” said Ruzo in a TED talk back in 2014. “The average temperature in the river was 86 degrees Celsius [187 degrees Fahrenheit], not quite boiling but definitely close enough … It’s not a legend.”
The most puzzling part was the sheer size of it.
Hot springs aren’t uncommon, and thermal pools get to these temperatures in other parts of the world, but nothing even comes close to the scope of the river – it’s up to 25 metres (82 feet) wide and 6 metres (19.6 feet) deep, and runs burning hot for an incredible 6.24 km (3.87 miles).
Add that to the fact that the river is around 700 km (435 miles) from the closest volcanic system, and the temperature just didn’t make any sense. In fact, it’s the only river of its kind anywhere in the world that we know of.
With the permission of the local Shaman, Ruzo has spent recent years studying the river, its surrounding ecosystem, and its water in the lab, in the hopes of figuring out what’s going on.