Amazing Caves: Pictures of the Earth's Innards

Altamira Bison

Altamira Cave Paleolithic cave painting in Spain.

(Image credit: MNCN-CSIS, Spain)

A painted bison on the ceiling of Altamira cave in Spain. The cave is closed to the public because human incursions have caused damage to the 14,000-year-old paintings.

Altamira Cave Deer

Painted deer decorate Altamira Cave in Spain.

(Image credit: MNCN-CSIS, Spain)

A deer painted in Altamira Cave's "Polychrome Hall," a passage full of red ochre Paleolithic paintings. To the lower left are sensors to measure temperature and humidity in the cave.

Polychrome Hall, Altamira

Paintings on the ceiling of Altamira Cave.

(Image credit: MNCN-CSIS, Spain)

Rocky Polychrome Hall in Altamira Cave has been compared to a Paleolithic Sistine Chapel because of its decorated ceiling.

Leaving a Mark

Paleolithic handprint paintings in Argentina.

(Image credit: Pablo H Caridad, Shutterstock)

Paleolithic cave paintings in Argentina. In Cueva de las Manos (Cave of the Hands) in Patagonia, people decorated cave walls with handprints at least 9,000 years ago.

Blue Hole

The blue caves of Zakynthos

(Image credit: © Alicja Ludwikowska |

The "blue caves" along the Greek island of Zakynthos are accessible only by sea. Sunlight reflecting off the water gives these caves their blue hue, making them popular for boating and diving.

Frozen Rock

Stalactites in a cave in France.

(Image credit: CREDIT: © Elena Elisseeva |

Stalactites drip from the ceiling in a cave in the Dordogne region of France. These rock formations form when mineral-laden water drips through the cave, leaving behind calcium carbonate or other minerals. Water that falls onto the ground below from the growing stalactite can form stalagmites. When these ground formations meet up with the ceiling formations, the result is a "column."

Sulphur Cave

Kaklik cave formations in Turkey are fed by Sulphur.

(Image credit: CREDIT: © Softdreams |

The Kaklik cave in Turkey is fed by sulphur-filled waters, which create these white formations not unlike those seen at Mammoth Springs in Yellowstone National Park. The water's sulphur content gives these caves a stinky rotten-egg smell.

Hidden World

The Mulu Caves in Borneo are among the world's largest.

(Image credit: CREDIT: © Torsius |

The Mulu Caves in Borneo are some of the most expansive on Earth. Carved out of limestone in Gunung Mulu National Park, the caves span at least 225 miles (362 kilometers) of underground passages.

Like a Flowing Stone

Cave formation in Greece.

(Image credit: Konstantinos Kourtidis, Demokritus University of Thrace, distrbuted by EGU under a Creative Commons License)

A cave wall on the island of Antiparos, Greece. Cave formations such as stalactites and stalagmites are known by geologists as "speleothems."

Showy Cavern

Borgio Verezzi cavern in Italy is open to the public.

(Image credit: Daniele Silva, Shutterstock)

Borgio Verezzi cavern in Italy was discovered by three young boys in 1933. It's now open for the public to view the stalactite and stalagmite formations inside.

Underground Wonderland

The Reed Flute caves in Guangxi, China

(Image credit: David Davis, Shutterstock)

Even today, humans can't help but jazz up caves. The Reed Flute caves in the Guangxi Province of China are illuminated with colored lights to highlight their formations.

Stephanie Pappas
Live Science Contributor

Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.