Season 2 closes with a four-month raft trek down the Nile is chronicled. Included: confrontations with alligators and bandits; the Tissisat Falls in Ethiopia; the black pyramids of Meroe; 12th-century churches.
The health of the South Pacific's major coral reefs is gauged by Jean-Michel Cousteau, ocean explorers Howard and Michele Hall, deep-reef scientist Richard Pyle and Fijian diver Rusi Vulakoro. Included: how coral reefs are formed. Liam Neeson narrates.