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 ...

A hollow then exists once the lava stops flowing. Even better than the cave at Mare Tranquillitatis, would be the discovery of other such structures near either of the lunar poles. Astronauts ...

You don’t have to be a hardcore spelunker (cave explorer) to get awed by caves in Oregon. This may be my favorite. It’s a ...

The Canary Islands not only boast the third largest volcano in the world, but also the largest natural underwater lava tunnel ... and a blend of dry and submerged cave sections.

Larisa Pozdnyakova’s words, in her thick Russian accent, float to me from within the cave’s seemingly endless black void. Apparently, she can read my mind: All I can think about is not getting ...