Impossible Planet

A man reveals the incredible science he used to answer how Australia's Lake Hillier gets its bubblegum-pink color. Then, the black sand at Iceland's Diamond Beach is dotted with glacial ice, and China's Shilin Stone Forest captivates and mystifies.

Geologists explain the phenomena behind beautifully rounded boulders in New Zealand. Then, Chinese mountains covered in turquoise, lavender, magenta and gold are explored, and caves in Australia feature intricate limestone crystal formations.

The cause behind the shimmering blue waves off the coast of Australia is uncovered. Then, Australia's Karijini gorges are some of the oldest in existence, and a volcanic region of Iceland has bubbling potholes that create an otherworldly atmosphere.

A professor shares fascinating new discoveries surrounding an ancient monument, the Giant's Causeway, in Northern Ireland. Then, a busy, modern metropolis collides with ancient archaeological evidence at Los Angeles' La Brea Tar Pits.

We get a closer look at geysers at a US national park and a geothermal field in Iceland. Then, a stack of pancake-shaped rock formations bewilders passersby in New Zealand, and approximately 50 million crabs journey across Christmas Island, Australia.

Russia's Lake Baikal, famous for being the largest, oldest and deepest freshwater lake on Earth, is explored. Then, the cause behind the frothy waves of "Cappuccino Coasts" is explained, and the oldest-known caves in the world are uncovered.

Thousands of giant spider crabs undertake an epic migration in Australia. Then, mammoth ice caves are explored in Iceland, and the story behind unusual rock formations that created natural castles in Turkey is revealed.

Nambung National Park in Australia is home to some curious formations and a fascinating desert, just minutes from the ocean. Then a permafrost cave in Iceland and an unreal landscape in Turkey are explored.

The secrets behind the famous northern and southern lights are revealed. Then, a series of sink holes in Mexico offer a window to a spectacular underwater cave system, and eternal flames flicker in a New Zealand forest, but never burn it down.

Incredible geological formations, including columns that appear to defy gravity, are explored in Iceland. Then, millions of luminescent worms light up caves in New Zealand, and the Wave Rock in Australia gets its name from a very obvious feature.