What on Earth?

Six breath-taking images, six unfathomable mysteries; from a gigantic tsunami hundreds of feet high that never hits land, to a secret underground base in China and has an image from space finally revealed the location of the Garden of Eden?

Strange barren rings in the Namib Desert; an island the size of Manhattan disappears without trace; a lost city in the middle of the Amazonian jungle.

How the Eye of the Sahara, a beautiful 25 mile structure, is formed remains a mystery; incredible clouds emanating from an island in the Indian Ocean could be evidence of a terrifying new weather weapon.

NASA astronaut Mike Barratt explains photographing a strange ring in the ice on the world's oldest and most mysterious lake from the International Space Station; more rings on Lake Baikal have been seen.

Images of earth from space show an intimate portrait of human activity; cities glow bright while the wilderness remains dark, but the Australian outback is lit up like a series of vast cities.