THE WORLD OCEAN
But what of this environment into which, armed with the atom, we plunge with such enthusiasm and expectations? A portrait is in order, which must be brief, for not all the books ever written about the sea have yet described it fully.
The world ocean covers 70.8% of our planet. It contains 324,000,000 cubic miles of seawater. Living in it are upwards of a million different species of plants and animals. They range from one-celled organisms that can only be seen with a microscope to the largest creature ever to have lived on this earth—the giant blue (or sulfur-bottom) whale, captured specimens of which have exceeded 90 feet in length and 100 tons in weight.
The ocean’s depth ranges from 600 feet or less above continental shelves to more than 35,000 feet at the Marianas Trench. The mean depth is 12,451 feet. Sea bottom topography includes wide plains, the world’s longest mountain range, steeply rising individual truncated peaks called guyots (pronounced gee-ohs), gentle slopes, narrow canyons, and precipitous escarpments. Mountains higher than Everest rise from the ocean floor and never pierce the surface.
Underwater mountain traced by the Woods Hole Oceanographic Institution echo sounder in the Caribbean area. Depth is determined by the time it takes the sound emitted by the instrument to go to the bottom and return to the surface.