A large part of the remote, blue wilderness of the South Pacific is a marine desert. Many animals that live in the ocean, among them sharks, whales and turtles - must go to extraordinary lengths to survive. Tiger sharks travel hundreds of miles to feast on fledging albatross chicks and, every year, sperm whales journey from one side of the South Pacific to the other in their search for food and mates. Theirs is a journey that can end in tragedy.