One of the largest rivers in the world, the Congo is home to some of the world's most fascinating creatures. This program follows the 2,900-mile-long river on its journey from its source in Zambia through marshland and rainforests. The shoebill, elephant fish and blind eel are just some of the wildlife in the area some biologists call the cradle of evolution. The river also causes chimpanzees and bonobos, who live on opposite sides of the Congo, to have completely different social systems despite being anatomically similar. Further down the line, where the river flows into the Atlantic Ocean, newborn turtles begin their lifelong battle against the ocean.