Located in the Western Pacific Ocean, approximately 124 miles east of the Mariana Islands, the Mariana Trench features the deepest natural point in the world. An oceanic trench, is a topographical depression in the sea floor, which is relatively narrower in width as compared to its length. The Mariana Trench, is a crescent shaped trough in the Earth’s crust, averaging to about 1,580 miles long and 43 miles wide. The Trench, at its southern end, also projects a small steep-walled valley, called the Challenger Deep. It is the deepest known point on the Earth’s seabed, measuring to be 35,814 feet. Situated within the territories of the U.S. dependencies of Northern Mariana Islands and Guam, the Mariana Trench, was designated a U.S. National Monument in 2009.
The Trench is a distinctive morphological feature of the ‘convergent plate boundaries,’ also known as the ‘destructive plate boundary,’ along the lithospheric plate of the Earth. The movement of these plates towards each other leads to the flexing of the subducting slab and further descending beneath another lithospheric slab. The Mariana Trench, is part of the Izu-Bonin-Mariana subduction, that is divided by the two tectonic plates: Pacific plate and the Mariana plate. The Western edge of Pacific plate is subducted beneath the smaller Western Mariana plate. The Pacific plate being the oldest oceanic crust, possesses cooler and denser crust material. Hence, there exists great height difference in comparison to the Mariana plate, that is much younger.
Due to its extreme depths, the Trench is cloaked in utter darkness accompanied with extreme low temperatures. The water column above the bottom of the trench, exerts a crushing pressure of almost eight tons per square inch, recording a thousand times more than the standard atmospheric pressure at the sea level. Extending so far down, the trench, is still not part of the seafloor closest to the center of the Earth. This is owing to the Earth’s spheroid shape. Rather, certain parts of the Arctic Ocean seabed, are at least 8 miles closer to the Earth’s center, than the Challenger Deep seafloor.
The trench, has been area of curiosity for researchers over time. Yet, the first and the only time humans descended into the Challenger Deep was in 1960. Boarding a U.S. Navy submersible, a bathyscaphe named Trieste, Jacques Picard and Navy Lt. Don Walsh reached their goal of exploration. The onboard systems recorded a depth of 37,799 feet, which was later corrected to 35,814 feet. Consequently attempts were made in similar ways, but were unmanned. The ROVs Kaiko in 1996 and Nereus in 2009, recorded similar depths of 35,768 feet and 35, 814 feet respectively.
The most remarkable descent was made by the Canadian film director James Cameron in 2012. He reached the bottom of the Mariana Trench in the submersible vessel named Deepsea Challenger. In the process, he set a new world record depth for a solo descent.
Answering to some fundamental questions and addressing widespread curiosities, the expeditions have helped heed to some of them. The deep-ocean dredges and unmanned subs have given glimpses of large creatures living at the bottom of the Trench: Flatfish and Shrimp. According to Picard, “the bottom appeared light and clear, a waste of firm diatomaceous zone.” On the other hand, marine biologists reflected skeptic views on such sightings. Due to high and extreme pressure conditions, they firmly believe in the nonexistence of calcium, which would hence not sustain any vertebrates. The absence of calcium would imply that the bones of such creatures would simply dissolve. The collections from other explorations have also revealed some gigantic single celled amoebas inhabiting the Trench. Featuring size of greater than four inches, they are found in abundance on the seafloor and are also hosts to numerous organisms. In 2014, a new species of snailfish was discovered at a depth of 26,772 feet and in 2017 at the depth of 26,800 feet.
Intriguing facts and discoveries of the Trench, has kept mankind hooked onto research work. An understanding of the survival and existence of animals and organisms under such unfavorable conditions, can lead to breakthrough in medicines and biotechnology. Additionally, studying rocks and walls of the Trenches, aid in attaining better knowledge of the Earth’s interiors and tectonic plates-related phenomenon.
The recommendation of making the Trench a site for nuclear waste disposal, has faced large criticism across the world. The Trench, is seen as a subducting zone, that holds a capacity to eventually push the nuclear waste deep into the Earth’s mantle. Internationally, this act is frowned upon and is prohibited by law, as it may result in unforeseen repercussions, with long-term impact on mankind.