The major oceans (Atlantic, pacific, Indian, arctic, and antarctic) and their connectors and extensions cover approximately 70% of the earth’s surface physical factors dominate life in the ocean. Waves, tides, currents, salinities, temperatures, pressures, and light intensities largely determine the makeup of biological communities that, In turn, have considerable influence on the composition of bottom sediments and gases in solution. The food chains of the sea begin with the smallest know autographs and end with the largest of animals (giant fish, squid, and whales). The study of the physics, chemistry, geology, and biology of the sea are combined into a sort of ‘’super science’’ called oceanography, which is becoming increasingly important as an international force. Although exploration of the sea is not quite as expensive as exploration of outer space, a considerable outlay of ships, shore laboratories, equipment, and specialists are needed. Most research is of necessity carried out by a relatively few large institutions backed by government subsidies, mostly from the affluent nations.

         To fully appreciate both the promise and the problems involved in man’s use of the sea we need to look at the contour of the sea bottom which also gives standard oceanographic nomenclature for zones of the sea. According to the now widely accepted ‘’continental drift theory,’’ some of the continents, especially Africa and south America as one pair and Europe and north America as another, were once quite close together and have drifted apart through the ages. The mid – Atlantic ridge is , according to this theory, the line of former contact between continents now hundreds of miles apart. As a citizen you will be hearing a lot about the continental shelf, that sloping plateau that borders the continents. Located here are the bulk of undersea oil and mineral wealth. From the edge of the shelf, which varies greatly in width from location to location, the continental slope drops off rapidly into the true of the sea. The topography of the continental slope is very rugged with huge canyons and ridges that are constantly changing under the forces of volcanic action and underwater ‘’landslides’’

         Since there are likely to be phytoplankton under every square meter and since life in some form extends to the greatest depths, the seas are the largest and ‘’thickest’’ of ecosystems. They are also biologically the most diverse. Marine organisms exhibit an incredible array of adaptations, ranging from flotation devices that keep the tiny planters within the upper layers of water, to the huge mouths and stomachs of deep sea fish that live in a dark, cold world where meals are bulky but few and far between. As shown in this post the continental shelf areas are fairly productive, seafood harvested here is an important source of protein and minerals for man. The most productive areas and largest fisheries are those that benefit from nutrients carried up by upwelling currents, a form of energy subsidy. Strong upwelling occurs in certain areas along the west coasts of the several continents. The Peruvian upwelling region, one of the most productive natural areas in the world, was singled out for special discussion on this post. The vast stretches of the deep sea, however, are mostly semi desert with considerable total energy flow. (because f the large area) but not much per unit of area. The autotrophic layer (phonic zone) is so small in comparison with the tropospheric layer that the nutrient supply in the former is limiting. A number of schemes have been proposed, and there are now several experiments under way, to tap the potential energy of vertical temperature differences to create artificial upwelling. Even if man is not able to obtain much food from the deep – sea area it is nevertheless very important to him, for the seas act as a giant regulator that helps to moderate land climates and maintain favorable concentrations of carbon dioxide and oxygen in the atmosphere.

       International conferences are now being scheduled to discuss the thorny problem of setting up international law with rules and regulations for exploiting seabed minerals and energy resources. Since, as we have noted, most mineral wealth, as well as most exploitable food, is located near shore, it would seem reasonable for each country to assume stewardship of the shelf area adjacent to its land territory, but the large differences in width of the shelf make such a simple solution difficult, perhaps impractical. Most objective assessments (see, for example, cloud,1969) warn against undue optimism that the deep sea is a vast storehouse just waiting to be exploited. Recovering such resources as there are will be even more expensive than getting minerals and oil from the shelf where costs are indeed huge. Remember that sea is more important as a life support and climate regulator than it is as a supply depot. Anything we do to exploit the latter must not jeopardize the former (recall our point about ‘’gross and net’’energy).