“…we have better maps of the surface of Mars and the moon than we do the bottom of the ocean. We know very, very little about most of the ocean.” – Gene Feldman
The Challenger Deep is the deepest known point on Earth. Located at the southern end of the crescent-shaped Mariana Trench in the western Pacific Ocean, it lies approximately 124 miles east of the Mariana Islands.
The Mariana Trench
The Mariana Trench was formed by a process called subduction, when two tectonic plates meet and one is forced beneath the other.
In this case, the Pacific Plate, moving westward, is being forced under the Philippine Plate, which moves more slowly. The western edge of the Pacific Plate contains some of the oldest crust and mantle on Earth, making it heavier and denser. As a result, the Philippine Plate rides higher while the Pacific Plate is pushed downwards, creating a deep trough, the Mariana Trench.
The Discovery of the Challenger Deep
HMS Challenger (1875)
The Challenger Deep was first discovered in 1875 by the Royal Navy research vessel HMS Challenger. This pioneering ship undertook the world’s first global oceanographic expedition, a 3.5-year, 69,000-nautical-mile voyage.
Using a simple hemp line with iron sinkers attached, the crew recorded a depth of 4,475 fathoms (8,184 m / 26,850 ft) in the southern part of what is now known as the Mariana Trench.
HMS Challenger II (1951)
Fast forward to 1951, when another vessel, HMS Challenger II, conducted a depth sounding in the same area using echo-sounding technology. They recorded a new depth of 5,960 fathoms (10,900 m / 35,761 ft). The area was subsequently named Challenger Deep in honour of this vessel.
Measuring the Depth
The most recent precise measurement was taken in 2010 by the United States Center for Coastal & Ocean Mapping, which recorded a depth of 10,994 metres (36,070 ft or 6,011 fathoms) below sea level, with an estimated vertical accuracy of ±40 metres.
To put that into perspective, that’s around 7 miles deep, deeper than Mount Everest is tall (Everest stands at about 5.5 miles above sea level).
At this depth, in the Hadal zone, the pressure exceeds a staggering 16,000 psi. For comparison, the atmospheric pressure at sea level in your home is about 14.7 psi. These immense pressures make it extremely difficult to explore such deep regions of the ocean.
Image Credits
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Deep Ocean Trench – Credit: otlibrary.com
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Map of Challenger Deep (Mariana Trench) – Credit: COSEE-TEK / Google Earth
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HMS Challenger – Credit: North Wind Picture Archives / Alamy
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