Caves

Extreme sinkholes hold surprises inside.

Plant life thrives both inside and outside huge cave.

Son Doong cave big enough to hold a skyscraper.

Whether you think they're inviting or terrifying, caves are made from two tame ingredients.

Some 850 new species have been discovered in caves and underground caverns in Australian Outback.

Scientists have identified a previously unknown species of crustacean in an underwater cave.

Scientists explore caves to study the Earth’s history, as they dream of traveling back in time. In this case, to the Precambrian.

Geologists have differing theories on just how old the Grand Canyon is.

A mysterious fungus could be killing off bats.