The world's oceans continue to play a vital part in man's history on this planet. There is no doubt that in the long process of evolution man's early ancestors left the sea for the land. There is evidence too that some of these having progressed to the mammal stage returned to the sea to produce the dolphins, whales and seals. Some biologists believe that man's predecessors did likewise. Being driven by a shortage of food, they ventured into the shallow coastal waters to collect shell fish and other accessible sea food. During this period they lost much of their fur and learnt to swim. Unlike the aquatic mammals, they remained land animals. It must also be assumed that primitive man developed a great fear of the sea which remained with him even after he had developed the use of boats. Its storms, its vastness, its tides and its currents must have filled him with awe. Even in modern times seafaring occupations are considered hazardous pursuits and drowning as a cause of death is greatly dreaded. In the simple man's mind the dark ocean depths with unpredictable moods of violence create a sense of fear subconsciously supported by the fact that the newly born human being emerges from the dark and watery confines of the womb wherein it has, in its development, recapitulated the pattern of man's evolution. To return to explore the sea would be to retreat into the timeless past. It is not surprising, therefore, that extensive exploration of the sea and sea bed has lagged behind the extension of man's activity over the great land masses, the conquest of the highest mountains, the development of flight and in later years the conquest of space.