GREAT NATURE -- Chile's Island of Extremes: Madre de Dios

Just off the coast of Chile lies one of the world's most weather-beaten and inhospitable islands -- Madres De Dios. This island has been shaped by torrential rain and hides a labyrinth of caves. Now a team of filmmakers brave violent seas in pursuit of the island's secrets. See how rain sculpts an alien-like landscape of rock and stone, discover an ancient forest unchanged for millions of years, and risk going deep into an unknown, subterranean world to reveal the island's incredible, explosive past.