From the day the first humans put to sea 50,000 years ago, the ocean has never lost its power to fascinate mankind. This fascination endures despite -- or, perhaps, because of -- the ever-present danger that has been, for a thousand generations, the cost of seafaring: shipwrecks. From prehistoric dugouts to the Titanic herself, new discoveries, and thousands of old ones, retain a firm grip on the imagination of the world; they remain a source of dread and fascination, an example of human frailty in the face of nature's power.