This photo by NASA's Mars Reconnaissance Orbiter shows a cave skylight roughly 35 meters across and 20 meters deep. Caves often form in volcanic regions when lava flows solidify on top ...

A dazzling type of actinomycete coats several cave areas at Lava Beds National Monument. Image courtesy of National Park Service A hint of vegetation among the ancient lava rubble at Lava Beds ...

Approximately 700,000 years ago when molten rock erupted from a vent in nearby Hart Prairie, the mile-long Lava River Cave was formed. Today, visitors can explore the cave's cool, dark expanse by ...

Through the intricate study of lava tubes—caves formed following volcanic eruptions when lava cools down—an international team of researchers has uncovered clues about Earth's ancient ...

It seems to be an empty lava tube. The study, published in Nature Astronomy, is the result of an international collaboration. "These caves have been theorized for over 50 years, but it is the ...

At the top of our list is the lava cave in Arizona where you can hike one mile underground through an actual lava tube. The Lava River Cave in Flagstaff, AZ is a one-mile-long lava tube that ...