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 balmy tropical Atlantic, everything from dolphins, manatees and whale sharks to sunbathing jellyfish thrive in the Caribbean's warm, sheltered waters, fringed with coral reefs and rich mangrove forests.