Melanie Naff, age 10, of Phoenix, Arizona, for her question:

How deep is the Pacific Ocean?

This depends on just where you dip down. The floor of the vast Pacific has a lot of bumpy ups and downs and some parts are much deeper than others. Near the shores, the water is not deep enough to reach your ankles, especially when the tide goes out. But farther out to sea, it gets deeper and deeper and deeper. About 20 miles from the shore, the water below your boat may be about 500 feet deep. Then the sea bed dips down a huge, underwater cliff to the bottom of the great ocean basin.

The average depth of the great ocean is about 14,000 feet, or nearly 2 1/2 miles. But there are lone mountains and mighty ranges on its bumpy floor. There are also deep valleys and canyons. About 200 miles from the island of Guam, there is an underwater trench that dips 36,198 feet below the surface waves. So far as we know, this is the deepest spot in the Pacific    or in any other ocean.