Young animals prepare for their first winter away from their parents, humpback whales return to Alaska's rich feeding grounds and salmon return to spawn in the rivers where they were hatched. But the returning salmon have to negotiate a path past hungry brown bears fattening themselves before they hibernate.
It is an unexpected and contrasting journey through America's iconic and varied landscapes as the Mississippi flows from source to mouth. The Mississippi's greatest surprise is its incredible reach. Its fingers stretch into nearly half of the USA, collecting water from 31 states. More than any other, this one river has helped unite the many and varied parts of America.
Nine miles off the coast of Oman, a zebra shark scans the ocean floor for crustaceans, while a menacing giant stingray floats by. Soon, night becomes day and new killers emerge, from toxic scorpion fish to crown-of-thorns starfish, both bringing coral devastation. Dive among these deadly marine carnivores.