Mars skylights like this could be the mouths of caves formed by lava tubes. NASA wants to explore them. Credit: NASA / JPL-Caltech / Univ. of Arizona Ever since scientists have had an orbiter's view of Mars, they've observed intriguing black spots on the ...

Planning a trip to Mammoth Cave National Park? These essential tips will help you choose the right tour, avoid crowds, prepare for cave conditions, and make the most of your visit.

On Sunday’s episode of The Excerpt podcast: Hidden beneath Earth’s surface are caverns and pathways that hold the secrets of our planet’s very beginnings. Even after decades of exploration, there are still new ecosystems and signs of past lives yet ...

The discovery of more than 100 prehistoric structures in the Cova Dones cave in Spain makes it one of the most significant prehistoric underground sites in the world. Archaeologists found stalagmites intentionally reassembled within the caves, dating them ...