The average ocean depth is 3.7 kilometers (2.3 miles). NOAA Office of Ocean Exploration; Dr. Bob Embley, NOAA PMEL, Chief Scientist.
Officially anything deeper than just 200 metres is considered the “deep sea”, but the average depth of the entire ocean is about 3.5km and the deepest point – the Challenger Deep in the Mariana Trench, in the western Pacific – is a little short of 11km down.
The depths from 1,000-4,000 meters (3,300 - 13,100 feet) comprise the bathypelagic zone. Due to its constant darkness, this zone is also called the midnight zone. The only light at this depth and lower comes from the bioluminescence of the animals themselves.
The Mariana Trench, in the Pacific Ocean, is the deepest location on Earth. According to the Exclusive Economic Zone (EEZ), the United States has jurisdiction over the trench and its resources. Scientists use a variety of technologies to overcome the challenges of deep-sea exploration and explore the Trench.
However, in terms of average depth, the Pacific Ocean is the deepest. Though calculations vary, it is estimated that the entire ocean floor averages about 4,280 meters (14,042 ft), which is over 500 m (1640 ft) deeper than the global average of 3,700 meters (12,100 ft).
Last year an expedition to the Mariana Trench made history by conducting the deepest crewed dive ever completed as it descended 10,927 metres into the Challenger Deep.
While thousands of climbers have successfully scaled Mount Everest, the highest point on Earth, only two people have descended to the planet's deepest point, the Challenger Deep in the Pacific Ocean's Mariana Trench.
The waters of the Pacific Ocean comprise the world's largest heat reservoir, by far, and it is the warmest ocean, overall, of the world's five oceans. (The other oceans are the Arctic, Antarctic and Indian Oceans.)
Southern Ocean
It is also known as the Antarctic Ocean as it surrounds Antarctica. It is the coldest and wildest ocean in the world.
More than eighty percent of our ocean is unmapped, unobserved, and unexplored. Much remains to be learned from exploring the mysteries of the deep.
Mariana Trench. Imagine the deepest, darkest place on Earth—an underwater trench plummeting to a depth of 35,800 feet, nearly seven miles below the ocean surface.
Light in the ocean decreases with depth, with minimal light penetrating between 200-1,000 meters (656-3,280 feet) and depths below 1,000 meters receiving no light from the surface.
Features of the ocean include the continental shelf, slope, and rise. The ocean floor is called the abyssal plain. Below the ocean floor, there are a few small deeper areas called ocean trenches. Features rising up from the ocean floor include seamounts, volcanic islands and the mid-oceanic ridges and rises.
That means that most people can dive up to a maximum of 60 feet safely. For most swimmers, a depth of 20 feet (6.09 meters) is the most they will free dive. Experienced divers can safely dive to a depth of 40 feet (12.19 meters) when exploring underwater reefs.
Deep sea amoebas, shrimp-like creatures, and sea cucumbers live at the bottom of the Mariana Trench. Mariana Trench animals include xenophyophores, amphipods, and small sea cucumbers (holothurians) which all dwell at the bottom of the ocean's deepest depression.
“The intense pressures in the deep ocean make it an extremely difficult environment to explore.” Although you don't notice it, the pressure of the air pushing down on your body at sea level is about 15 pounds per square inch. If you went up into space, above the Earth's atmosphere, the pressure would decrease to zero.
The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 10,935 meters (35,876 feet) deep.
The Pacific Ocean is the largest and deepest of the world ocean basins. Covering approximately 63 million square miles and containing more than half of the free water on Earth, the Pacific is by far the largest of the world's ocean basins. All of the world's continents could fit into the Pacific basin.
But as in weather, where there are areas of high and low pressure, the ocean has areas of high and low salinity. Of the five ocean basins, the Atlantic Ocean is the saltiest. On average, there is a distinct decrease in salinity near the equator and at both poles, although for different reasons.
The quick answer to which side of Australia has warmer waters is the Northern coast in the Northern Territory with temperatures lingering around 28 to 32 degrees Celcius all year round.
What is the coldest place in the world? It is a high ridge in Antarctica on the East Antarctic Plateau where temperatures in several hollows can dip below minus 133.6° Fahrenheit (minus 92° Celsius) on a clear winter night - colder than the previous recorded low temperature.
These variations in solar energy mean that the ocean surface can vary in temperature from a warm 30°C (86°F) in the tropics to a very cold -2°C (28°F) near the poles.
Trieste is a Swiss-designed, Italian-built deep-diving research bathyscaphe which reached a record depth of about 10,911 metres (35,797 ft) in the Challenger Deep of the Mariana Trench near Guam in the Pacific.
Despite its size and impact on the lives of every organism on Earth, the ocean remains a mystery. More than 80 percent of the ocean has never been mapped, explored, or even seen by humans. A far greater percentage of the surfaces of the moon and the planet Mars has been mapped and studied than of our own ocean floor.
In 1960, Navy Lt. Don Walsh (along with Swiss oceanographer Jacques Piccard) became the first person to descend to the deepest part of the ocean, the Challenger Deep in the Mariana Trench. Walsh went on to teach ocean engineering, and remains a passionate advocate of ocean exploration.