More than one hundred and fifty years ago Thomas Gray, in his famous “Elegy Written in a Country Churchyard” penned these lines:
"Full many a gem of purest rays serene,
The dark, unfathomed caves of ocean bear."
Until the middle of the nineteenth century very little was known of the immense ocean depths. Speculation and imagination had been rife with regard to the life and conditions below the surface of the ocean, but little definite knowledge had as yet been gleaned.
Towards the close of the year 1872, H.M.S, “Challenger” sailed from Portsmouth on a voyage round the world, which lasted for three and a half years. The main object of this cruise was to investigate the physical conditions and natural history of the deep sea in various parts of the world. The ship was equipped with special apparatus for sounding and dredging purposes, for obtaining specimens of sea-water and its inhabitants at various depths, for testing the temperature of the ocean, and for preserving specimens for subsequent observation and examination. This expedition accumulated a vast quantity of facts, statistics, and specimens, and its scientific results proved to be of incalculable value. A great many sciences were enriched by this accumulation of new facts. The success of the expedition was altogether beyond the expectations of its promoters. In fact, as an outcome of this cruise a new science, which we call “oceanography," had its birth.
Glimpses were now obtained of the fascinating world below the level of the ocean, the countless and diverse forms exhibited by animal life and plant life; the numerous battles fought with the greatest courage and desperation between the different inhabitants of the ocean, sometimes between members of the same species; the beauties of the flora or plant world; the innumerable low forms of life, invisible to the naked eye; the nature and composition of the floor of the ocean, and many other things. We began to learn something of the deep and almost unfathomable secrets of the mighty and mysterious ocean.
The trawlings and dredgings carried out by the “Challenger" disclosed the fact that animal life exists at all depths, and that the ocean bed itself consists of different kinds of mud, or slime, called ooze, which is in some places blue, in others red, and in others green. Much of this ooze, it was afterwards discovered, is composed of the remains of minute forms of animal life known as animalculæ. It also contains shells and the teeth and bones of larger animals. The “Challenger” expedition discovered, too, by a long series of soundings, that the deepest part of the ocean, away in the far Pacific, was 4,500 fathoms, or 27,000 feet. More recent soundings, however, have given the deepest part of the Pacific Ocean as over 32,000 feet, or slightly more than six miles. Can we realise what this really means? If we could take Mount Everest, in India, the highest mountain peak in the world, and place it in the deepest part of the Pacific Ocean, the peak would be three thousand feet below the level of the ocean.
Thomas Gray (1716-1771)
Oceanography (or oceanology)