Sir David Attenborough narrates this 48:21 documentary. Fresh water 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 in the world's deepest lake. Planet Earth captures 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.