Most of Australia lies underwater. Its marine wilderness is double that of its landmass.

Journeying in this episode through Australia's three surrounding oceans and their islands, we discover an explosion of life in the cold, spectacular southern sea, the sanctuary of the Pacific and the Indian Ocean with its awe-inspiring predators.

The force of human induced change has been rapid and dramatic, so animal populations have reacted in rapid and dramatic ways. In this episode we meet Australia's contemporary success stories, & those being left behind.