Walking into Fingal's Cave is like walking into the heart of the Earth. Here among the towering basalt columns, the visitor stands inside a lava flow. Magma that swelled up from deep in the Earth ...
Take an otherworldly journey through Hang Son Doong, the world's largest cave located in Vietnam. The cave is more than 500 feet tall, 650 feet wide, and 29,500 feet long. Video courtesy of Ryan ...
Discovered in 1999 inside an abandoned mine in Southern Spain, Pulpí Geode is the largest crystal 'cave' of its kind in the world. But what exactly is a geode and how do crystals form inside them?