A crew of mariners, scientists and filmmakers are followed as they cast off on the Sedna IV, an oceanographic schooner, to sail around the world exploring the beauty of nature, how ecosystems work and conservation challenges facing the planet. 　　1 The Sharks of Cocos Island 　　Highlighting efforts to save the sharks of Cocos from overfishing 　　2 The Song of the Humpback 　　Scientists att...