Located in Peru, this boiling river is such a mystery because while hot springs are not uncommon, they're usually located near volcanoes. This river is more than 700 km (435 miles) from nearest volcanic center.
Ruzo says the most amazing thing about it is its size. Even hot springs near volcanoes usually aren't this big. The river's wider than a two lane road and has an average temperature of 86 degrees Celsius or 186.8 degrees Fahrenheit.
In fact, the river's hot enough to kill most animals that are unlucky enough to fall into it, like this poor frog. In Ruzo's 2014 TED Talk, he explains the gruesome details. He's seen several creatures meet their fate this way.
While Ruzo located the river, he does not claim to have discovered it. He told IFLScience that it's "been known about by indigenous Amazonian communities for centuries." Local shamans, like the one pictured here, say the river gets its heat from a serpent spirit called Yacumama.
The scientific source of the heat remains the big question. Ruzo's tests have found that the water originally fell as rain, but where it actually landed is still a mystery. After falling as rain, it most likely seeped into the ground and was heated by Earth's geothermal energy before re-surfacing in the Amazon.
Ruzo is not only studying the origins of the boiling river water. He's also working with microbial ecologists to study the extremophiles, organisms that are able to live in extreme environments, that somehow survive in the river's super hot waters.
Most importantly, Ruzo is working to save the river. So much of the Amazon has been destroyed and he recognizes that if he doesn't work to show the world how incredibly important this environment is to the survival of the planet and its people, it may not be around forever.