A cave is "a natural opening in the ground extending beyond the zone of light and large enough to permit the entry of man," according to the U.S. Geological Survey. Caves can range in size from single rooms to large formations with winding passageways that extend for miles. Caves typically form in types of rock, such as limestone, that dissolve in water. It can take tens of thousands to hundreds of thousands of years for caves to form. The study of caves is called speleology, and the exploration of caves is called spelunking. Caves are famous of their dripstone features called speleothems, the most well-known of which are stalactites and stalagmites. Many of the strange creatures found in caves have adapted to live in near or total darkness — some are blind to visible light. See cave pictures and read about the latest cave discoveries and speleological research below.
Latest about caves
35,000-year-old 'tortoise shell' carving may be Holy Land's oldest evidence of ritual behavior
A carved boulder found deep in a cave in Israel may have been used for rituals more than 35,000 years ago.
Marble Caves: Chile's ethereal turquoise caverns with 'mineral ice cream' on the walls
The Marble Caves sit on the shores of a turquoise glacial lake in southern Chile. Light bounces off the water onto the walls, creating a magical, ever-changing display inside the caverns.
Hang Son Doong: The world's biggest cave, so 'outrageous in size' it fits 2 jungles and the 'Great Wall of Vietnam'
Vietnam's Son Doong cave is so large, you could squeeze 15 Great Pyramids of Giza inside it and fly a Boeing 747 airplane through some of its passages.
Cave of Swimmers: 9,000-year-old rock art of people swimming in what's now the arid Sahara
This series of paintings, found inside a cave in the Sahara, shows a pair of swimmers.
16,000-year-old skeleton, crystals and stone tools discovered in Malaysian caves
Archaeologists think the earliest skeleton from the Malaysian excavation may be up to 16,000 years old.
Ancient submerged bridge in Spain reveals that humans inhabited Mediterranean island nearly 6,000 years ago
After analyzing a submerged bridge found in a Spanish cave, researchers have determined that humans inhabited the area earlier than previously thought.
Fairy Chimneys: The stone spires in Turkey that form 'the world's most unusual high-rise neighborhood'
Turkey's magical "fairy chimneys" in Cappadocia were carved out of an ancient volcanic landscape over millions of years before humans turned them into hiding dens.
500-year-old lion drawing in Puerto Rican cave may have been made by an enslaved African
There were no lions in 16th-century Puerto Rico — so was the cave drawing made by someone who'd actually seen one?
