Remote islands offer sanctuary for some of the planet's strangest and rarest creatures. The rare pygmy three-toed sloth enjoys a peaceful existence on an idyllic Caribbean island, while nesting albatross thrive in predator-free isolation. But island life always comes at a cost. On the Galapagos Islands, young marine iguana must escape an onslaught of deadly racer snakes the moment they hatch from the sand. On the sub-Antarctic island of Zavodovski, life gets more extreme still. Every day, one and a half million penguins risk being battered against the rocks by fierce waves as they try to get on and off the island.
In this episode Brian uncovers how the stunning diversity of shapes in the natural world are shadows of the rules that govern the universe. In Spain he shows how an attempt by hundreds of people to build the highest human tower reveals the force that shapes our planet. In Nepal, honey hunters seek out giant beehives that cling to cliff walls. The perfect hexagonal honeycombs made by the bees to store their honey conceal a mathematical rule. Off the coast of Canada, Brian explains how some of the most irregular, dangerous shapes in nature - massive icebergs that surge down from Greenland and into shipping lanes of the Atlantic - emerge from a powerful yet infinitely small force of nature. Even the most delicate six-sided snowflake tells a story of the forces of nature that forged it.
Fresh water is our most precious resource and it defines the distribution of life on land. Follow the descent of rivers from their mountain sources to the sea. Watch spectacular waterfalls, fly inside the Grand Canyon and explore the wildlife below the ice in the world's deepest lake. Witness unique and dramatic moments of animal behaviour: a showdown between smooth-coated otters and mugger crocodiles; deep-diving long tailed macaques; massive flocks of snow geese on the wing and a piranha frenzy in the perilous waters of the world's largest wetland.