Ben Hagen, age 11, of Monroe, La., for his question:
WHAT IS AN OCEAN DEEP?
A deep refers to any ocean area with a depth of more than 18,000 feet. More than 100 deeps have been found in ocean floors.
Contrary to popular belief, the deep is not found usually in the center of the ocean. Most of them occur close to mountainous islands where steep shores plunge down to the bottom of the sea.
Challenger Deep, in the Mariana Trench 200 miles southwest of Guam, is the deepest known ocean deep. There, the ocean floor is 36,198 feet below the surface.
Puerto Rico Trench, north of Puerto Rico, has the greatest recorded depth in the Atlantic. It was found in 1939 and has a depth of 28,374 feet.
A continental shelf extends along the shores of each continent bordering the Pacific Ocean. Here the water is seldom more than 600 feet deep.
The continental shelf that extends along the shores bordering the Atlantic ocean is about 500 feet deep.