For generations, indigenous tribes believed there were caverns hidden within the Auyán-tepuí tabletop mountain, in the rainforests of Venezuela. For cave explorer Francesco Sauro, who investigates the most remote undiscovered caves in the world, finding them was every bit as sacred.

After a two-decade search by geologists his team finally located caves there, known as Imawarì Yeuta, in March 2013, using satellite imagery and aerial surveys. Inside, they found an untouched world, with vivid violet lakes and minerals crystalized in the shape of vast eggs and mushrooms. “We were the first new creatures there for millions of years,” he says. “I was dreaming about it for months afterwards.”

The 31-year-old has become one of the most renowned explorers of his generation, and the discovery of Imawarì Yeuta, which at 50 to 70 million years old are the oldest caves in the world that can explored safely, is his crowning moment. He hopes studying these ancient, preserved worlds will help us to understand the origins of life.

Sauro has known caves all his life. His father was a cave explorer and first took his son inside the Lessini Mountains near Verona when he was three. He remembers feeling scared and crying but was not deterred. From age 18 he studied geology and almost immediately began leading cave explorations in his native Italy. For inspiration, he quotes Leonardo da Vinci, who wrote of his initial terror of gazing into a dark cave. “But slowly fear turns into curiosity about what is inside,” Sauro says.

Jim Naughten for TIME

Sauro and his team begin by scanning satellite images for hints of underground caves in the landscape before doing a fly-over to verify what they have found. To reach the caves they either use a helicopter, which can be logistically difficult and expensive, or trek and climb through dense forest, which can be slow and treacherous. His expeditions include geologists, topographers, biologists, physicists and topologists.

At Auyán-tepuí, he found the largest quartzite cave system in the world, with 14 miles (22.5 km) mapped so far. Up until now little has been known about this type of cave. In doing so he has discovered a new mineral and studied the bacterial colonies inside. Despite local legends, the biggest creatures he has found are spiders and centipedes. “Caves are witness to geographic history,” he says. “They preserve much more than the surface. They are archives of time, of the evolution of the landscape and life.”

Read More: How Talent—and a Little Luck—Got Saoirse Ronan to Hollywood

The biggest challenge, he says, is simply finding the entrance. Once inside, great care must be taken to avoid contamination. Careful paths are followed and all waste—including human waste—is painstakingly removed when the team leaves. His team is made up of Italians (La Venta Geographic Exploration), Venezuelans (Teraphosa Exploring Team) and Brazilians (Bambuí Speleological Research).

“The world is revealed by these caves,” says Sauro. “Below the surface is a dark continent which is mostly unknown but needs to be preserved and considered. As humans we need to start to think of the planet as not just what is on the surface. “In caves we can find hints of the origins of life.”

More Must-Reads from TIME

Contact us at

How Viral Librarian Mychal Threets Found His Joy
Poet Mosab Abu Toha Is Documenting War in Verse
Simone Manuel's Mission to Get Everybody to Swim
The Young Billionaire Using AI to Secure the Future of Japanese Businesses
RAYE Can’t Escape Her Success