David Breniser, age 7, of Lancaster, Pennsylvania, for his question:

Which ocean is the deepest?

The Pacific is the deepest and also the biggest in the world. Around the shores the water is shallow. But as the ocean floor gets farther from the land, it sinks gradually lower. Then, perhaps 100 miles or more from the shore, the seabed takes a mighty plunge. In many places it forms enormous underwater cliffs, often a mile high. These are the steep sides of the deep basin that holds most of the water in the Pacific Ocean.

On the floor of the basin there are underwater hills and valleys, mountain ranges and plunging ditches called trenches. Suppose we could take a giant bulldozer and level all the ups and downs on the ocean floor. The Pacific Ocean would be about 14,000 feet deep. One of its trenches is more than 36,000 feet deep. This is the deepest known pit in the world. The floor of the Atlantic has more huge mountains and valleys but the deepest known part of the world wide ocean is in the Pacific.