Episode one takes us to Antarctica - the coldest, windiest, most hostile continent. Only the toughest can survive here. From Weddell seals that grind back the ice with their teeth, to colourful starfish carpeting the seabed beneath the ice; huge colonies of king penguins crowd any ice-free land, and four-tonne elephant seals fight for territory on the beach.

Life comes here because the ocean that surrounds the continent is incredibly rich. Thousands of penguins, seals, albatross, and over a hundred great whales feast on krill baitballs. However, the ocean here is warming - and with that comes an uncertain future.