In the wild North Atlantic, massive whale pods, giant turtles and monstrous jellyfish ride the Gulf Stream, a huge ocean current that becomes a migration superhighway and helps warm northern Europe. Meanwhile, fishermen battle for survival in mountainous seas as they try to reap the current's natural fertility.

In the vast South Atlantic, huge pods of dolphins, massive penguin colonies and the largest gathering of marine mammals on earth pack chains of extraordinary islands, created by powerful volcanic forces far below them. Nutrient-rich upwellings create profusions of life in some areas, whilst extreme isolation and abyssal depths host a world of bizarre creatures in others.