"Planet Earth, Vol. 2" - "Caves" - Caves are one of the only habitats not directly driven by sunlight, but this doesn't mean there is no wildlife. This episode probes the mysterious, perpetual darkness and reveals the unknown underground world of caves, caverns and tunnels. "Deserts" - When astronauts peer down on Planet Earth, the one environment they all notice are the deserts, which make up a staggering 30 per cent of the land's surface. From space they look empty and lifeless. A closer look reveals a very different picture...Deserts are united by their lack of rain, yet they are the most varied of our planet's ecosystems. Mongolia's Gobi Desert is home to wild Bactrian camels, one of the rarest mammals on the planet, that survive by eating snow in lieu of water. In the Atacama in Chile, guanacos survive in the driest desert in the world by licking the dew from cactus spines. "Ice Worlds" - A journey to the polar extremes of our planet, where for most of the year the Arctic and Antarctic are locked in ice. As the sun abandons one pole and journeys to the other, these frozen worlds undergo the most extreme seasonal transformation on the planet - from the total darkness and numbing temperatures of the polar winter to the midnight sun of the summer, when the sun never sets.
• Subtitles: English