The Deepest Point in the Oceans

The 7-Mile Drop Is in the Mariana Trench in the Western Pacific

Champagne Vent at NW Eifuku Volcano, Mariana Trench MNM
Voyage To Inner Space - Exploring the Seas With NOAA Collection.

Pacific Ring of Fire 2004 Expedition/

NOAA Office of Ocean Exploration; Dr. Bob Embley, NOAA PMEL, Chief Scientist 

The Earth's oceans range in depth from the surface to more than 36,000 feet deep. The average depth clocks in at just over 2 miles, or about 12,100 feet. The deepest known point is nearly 7 miles below the surface.

Deepest Point in the World's Oceans

The oceans' deepest area is the Mariana Trench, also called the Marianas Trench, which is in the western part of the Pacific Ocean. The trench is 1,554 miles long and 44 miles wide, or 120 times larger than the Grand Canyon. According to the National Oceanic and Atmospheric Administration, the trench is almost 5 times wider than it is deep.

The deepest point of the trench is called Challenger Deep, after the British ship Challenger II, which discovered it on a 1951 surveying expedition. Challenger Deep lies at the southern end of the Mariana Trench near the Mariana Islands.

Various measurements have been taken of the ocean's depth at Challenger Deep, but it is usually described as 11,000 meters deep, or 6.84 miles beneath the ocean's surface. At 29,035 feet, Mount Everest is the tallest spot on Earth, yet if you submerged the mountain with its base at Challenger Deep, the peak would still be more than a mile below the surface.

The water pressure at Challenger Deep is 8 tons per square inch. By comparison, water pressure at a depth of 1 foot is just over 15 pounds per square inch.

Creation of the Mariana Trench

The Mariana Trench is at the convergence of two of the Earth's plates, the massive sections of the planet's rigid outer shell just below the crust. The Pacific plate is subducted or dives underneath, the Philippine plate. During this slow "dive," the Philippine plate was pulled down, which formed the trench.

Human Visits to the Bottom

Oceanographers Jacques Piccard and Don Walsh explored the Challenger Deep in January 1960 aboard a bathyscaphe named Trieste. The submersible carried the scientists 36,000 feet down, which took 5 hours. They could spend only 20 minutes on the sea floor, where they viewed an "ooze" and some shrimp and fish, although their view was hampered by sediment stirred up by their ship. The trip back to the surface took 3 hours.

On March 25, 2012, filmmaker and National Geographic Explorer James Cameron became the first person to make a solo voyage to the deepest point on Earth. His 24-foot tall submersible, the Deepsea Challenger, reached 35,756 feet (10,898 meters) after a 2.5-hour descent. Unlike Piccard and Walsh's brief visit, Cameron spent more than 3 hours exploring the trench, although his attempts to take biological samples were hampered by technical glitches.

Two unmanned submersibles—one from Japan and the other from the Woods Hole Oceanographic Institution in Massachusetts—have explored the Challenger Deep.

Marine Life in the Mariana Trench

Despite cold temperatures, extreme pressure, and lack of light, marine life does exist in the Mariana Trench. Single-celled protists called foraminifera, crustaceans, other invertebrates, and even fish have been found there.