6/6 Whales and sea lions alike journey to the seas off Alaska to feed on the plankton bloom. (R)
5/6 The great flood in the Okavango turns 4,000 square miles of arid plains into a wetland. (R)
4/6 A look at the sardine run, which happens each winter along the South African coast.
3/6 The story of a lion family's struggle to survive until the return of the great migration.