To the curious and the courageous, the sea still presents the challenge of the unknown, for ignorance is still the distinguishing characteristic of man’s relation to the sea. But now, more than ever, necessity urges us onward in our exploration of the sea. We now have submarines capable of staying under water for many months holding missiles capable of destruction many times greater than those used in World Waur Ⅱ．For strategic reasons，therefore，we need urgently to learn more about the ocean bottom．Quite apart from the threat of war，another necessity presses us to learn to master the sea．That necessity is basic to life itself：food．The lives of 2/3 of the world’s people are wholly dictated by that basic necessity；they are oppressed by hunger and by the weakness and disease which hunger generates．Out of the sea we can extract food to relieve the hunger of these millions of people and give dignity tO their lives．We must turn to the sea， because the bounty of the land has limits． What is the other reason for which we should learn to master the sea