by David Murphy
At its deepest points, the world's ocean system is deeper than our tallest mountains.
The average depth of the ocean is more than 12,000 feet. That's more than 2 miles. The deepest spot is the Mariana Trench in the western Pacific Ocean which drops roughly 7 miles below the surface. Closer to most coastlines, the continental shelf extends about 200 miles from the beach and only reaches a depth of about 460 feet. But beyond the shelf, you find the continental rise. The rise extends another 300 miles from shore. The bottom of that rise is about 3 miles deep. Beyond that, you have the deep ocean floor which varies in depth, depending on which ocean and which section of ocean you're talking about.
The reason the Pacific is home to the deepest water is because of the dynamics of what's going on beneath its surface. While the Atlantic is an earth crust formation zone with all its underwater volcanoes producing new sea floor, the Pacific is a crust-destroying zone. Around the perimeter of the Pacific are areas where old crust is being turned down beneath continents and melted. This creates deep trenches and canyons.