From strange new creatures that are only now being discovered to the treasures lying hidden in the inky depths, it is no wonder that oceanographers are calling this a golden age of oceanic discovery.
Gabrielle Walker explores why we know so little about the planet's oceans.
Gabrielle meets the oceanographers who have gone where so few have gone before - the deep ocean. They have made discoveries that the most imaginitive science-fiction writers would have trouble imagining. The deep ocean is the most unexplored part of our planet, and makes up more than 50 per cent of the Earth's surface.
She considers some of the remarkable resources that the oceans have to offer - from golden treasures lying hidden in the murky depths to possible new cures for cancer and antibiotic-resistant infections. She talks to oceanographers who are only just beginning to discover the oceans' potential and asks who owns the oceans and their valuable commodities.
Gabrielle examines the intimate relationship between the oceans and our climate. She finds out how the ocean currents influence the temperature of the planet and the important role oceans may play in protecting us from the damaging effects of global warming.