The Mariana Trench (Mariannes Trench in English) is one of the most fascinating and mysterious places on our planet. We are talking about the deepest point ever explored , populated by a unique biodiversity, with animals, fish and creatures that question every law of nature so far known. A place subject to continuous exploration, to be able to discover more about the mysteries of the underwater world.

Where is the Mariana Trench
The position is found in the North Pacific Ocean, east of the Mariana Islands. Geographical references are Japan to the north, the Philippine Islands to the west and Papua New Guinea to the south. It is an area very rich in underwater volcanoes, among other things at the meeting of two tectonic plates, the peaceful one and that of the Philippines. Precisely this meeting between the two plates has generated this depth, following the “sliding” of the peaceful plate under the other.

How deep
is Challenger Abyss, the deepest point ever recorded on the planet so far, measures almost 11 kilometers, 10,994 meters to be exact . To get an idea of ​​the depth, just think that if Everest, the highest mountain on earth (8,848 meters) were overturned, there would still be more than 2,000 meters.13 Burj Khalifa skyscrapers (838 m) placed one on top of the other would not be enough!
The official survey, which reached and recorded this depth, was on December 7, 2011. Before that, the surveys had stopped first at 8,184 meters (1872-1876, Challenger expedition), then at 9,636 meters (1899, Black US coal mine) , and 10,863 meters (1951, Royal Navy Challenger II vessel).

Other technical information, data and surveys

  • Depth : 10,994 meters (measured on the deepest point known as the Challenger Abyss)
  • Where is it : 11 ° 21 ‘north latitude, 142 ° 12’ east longitude (Pacific Ocean, east of the Mariana Islands, between Japan, the Philippines and New Guinea)
  • Pressure : 1,100 Kg per cm2 (more than 1,100 times the normal atmospheric). Basically, at those depths one cm2 of water weighs a ton
  • Temperature : about 3 °. Despite the depth, the temperature is mitigated by the presence of numerous underwater volcanoes
  • First expedition : 1960, Bathyscaphe Trieste
  • Latest expedition : June 7, 2020. Kathy Sullivan is the first woman to descend into the Mariana Trench, after also being the first female astronaut to walk in space

Mercury and plastic pollution
Even here, in one of the most inaccessible places on the planet, man has managed to poison the ecosystem. The chilling discovery has been made and confirmed multiple times .
Already in the expedition of the Texan Victor Vescovo, in May 2019, plastic waste had been found in the depths of the ocean. Subsequently, a group of Chinese and American researchers found the presence of mercury and plastic in the ecosystem at a depth of almost 10 thousand meters .
This is a dramatic discovery, as methylmercury was thought to accumulate only up to a few hundred meters deep.
The implications of the discovery are dramatic:this means that mercury and plastic have in fact entered the food chain at all levels . Small crustaceans and molluscs, even in the deepest abysses, ingest plastic; these organisms are in turn eaten by larger fish, and so on in an unbroken chain. This happens and has happened even in the new indigenous life forms discovered in the Mariana Trench: these had ingested plastic and had traces of mercury. And only in part is it the mercury produced naturally by eruptions; according to scientists, much of the presence is due to human activities, such as the extraction and combustion of coal, peat and wood both at an industrial and domestic level, related to the production of electricity or other activities.

Visiting the Mariana Trench is possible, but it costs a little
The director James Cameron on March 26, 2012 I organize a dive with the Deepsea Challenger submarine, successfully reaching the bottom of the trench (at 10,894 m) and becoming the third man to make the company, as well as the first to go solo. Then follow the Texan billionaire Victor Vescovo in 2019, reaching an altitude of 10,924 meters.
But now there is even a submarine cruise in the depths of the trench available : a cruise 11,000 meters underwater, aboard the Limiting Factor submarine of Eyos Expeditions. Small detail… it costs about 700 thousand euros per person! Safety is guaranteed by 9 cm thick titanium plates. The duration of the cruise is 14 hours, 8 of which to descend and ascend (4 + 4)

Life forms, legendary fish and aquatic monsters
Photo by Hans Hillewaert. Given the conditions, it is already surprising that there is any form of life. The absence of light (the sunlight only penetrates up to 150 meters deep), the impressive pressure (over a thousand times the normal atmosphere), the rarefied oxygen, make the proliferation of life a real mystery.
Yet already the lieutenant Don Walsh and Jacques Piccard, in the immersion of the Bathyscaphe Trieste on 23 January 1960, were able to see absolutely unique life forms: particular species of sole or plaice, diatoms (unicellular algae) and even some shrimps.
The Challenger expedition subsequently revealed the presence of various native species of the pit : crustaceans very similar to Pacific shrimps, but with gigantic dimensions (between 17 and 30 cm), holothurias (animals in the shape of twigs that feed on the debris in the bottom), and other small life forms with soft calcium carbonate tentacles and shells.
More on the surface (so to speak …), at about 8,145 meters, the researchers then sighted what was baptized ” Ghost Fish .“(Ghost Fish): it is a rather pale fish, almost transparent, in the shape of a paper handkerchief abandoned in the sea, but with very thin fins that cut through the water almost without moving it. The transparent body even allows glimpses of the internal organs (see the video at minute 1:45).
Finally, more recently (between 2014 and 2017) the researchers discovered a new creature over 8,000 meters , near the Island of Guam. Snail fish “, a 20 cm long liparidae with a translucent pink color that feeds on small crustaceans.

The Megalodon, the largest shark ever lived
Photo by Sergiodlarosa.
Photo by Dr. Alton C. Dooley. In recent times, rumors have even spread that the Megalodon (Carcharocles megalodon), believed to have been extinct for several million years, continued to live in the Mariana Trench. This monster of 18 meters and with a mandibular opening of about 2 meters in reality is as beautiful as extinct, and the rumors have been completely dismantled by the scientific community.

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