In this companion book to the television series, six of the most spectacular natural phenomena on our planet are explored--the flooding of the Okavango Delta in Botswana; the melting of 10 million square kilometers of ice in the Arctic; the migration of the Serengeti; the great salmon run in British Columbia; the explosion of sea life in Alaska's coastal waters; and perhaps the greatest marine spectacle on the planet, the annual tide of sardines along South Africa's east coast.