Flowing through Peru’s rainforest is a roughly four-mile stretch of water known as the Boiling River. Fed by geothermal springs, it reaches more than 200°F—hot enough to kill animals that slip into its path. The river has long been the stuff of legend, even dismissed by some Peruvians as nonexistent.

But to Rosa Vásquez Espinoza, a Lima-born chemical biologist and National Geographic Explorer, the Boiling River is very real. As the creator of MicroAmazon, a multidisciplinary examination of the rainforest at its tiniest, she’s studying the microbes in the river’s extreme environment. “No one has ever explored these organisms,” says David Sherman, head of the University of Michigan lab where Vásquez Espinoza is