Two distinct marine worlds meet in the waters that encircle Australia. In its long voyage into isolation following its breakaway from Gondwana, 45 million years ago, the island continent came to span both tropical and temperate seas. Today its shores are ringed by the most diverse assemblies of marine life on earth. This program recounts the making of this unique Australia down under, from the storm tossed kelp forests of the cool south, to the magic splendours of the Great Barrier Reef. The program begins its story where Australia was born, in the southern latitudes of the Antarctic seas. Antarctica is the last remnant of Gondwana - it froze over after the other continents broke away, but its cool rich waters still generate a wealth of nutrients which, carried by the deep currents, sustain Australia's marine life.