The tiger forest marks the end of our journey through the Arctic, from the frozen ocean down across the lands that surround it. The other end of our planet, the Antarctic is starkly different, a frozen continent completely surrounded by ocean. Icebergs here are so large that they're measured in miles, not meters. They are the only obstacles in the path of giant waves which circle around the continent untramped by other lands.

These seas may be cold and storm-racked, but they are bursting with life. No bird is more at home in water and they are masterful surfers. Penguins are found only in the southern hemisphere. They can't fly, but they don't need to. There are no polar bears here. These are gentoo penguins. Each spring they come ashore to lay their eggs and rear their young. Their hungry chicks demands so much seafood that both parents have to go fishing.