The Great Mariana Trench is located in the Southwest of Guam island, which is known as the largest and the eastern most island of the Mariana Island Chain right between Japan and Indonesia. It is the deepest point on Earth. As the result of the research, conducted by the scientists determined that its deepest point is 10.994. It is also determined that it runs for 2542 kilometers and the width of the trench is 69 kilometers.
To explain how the Mariana Trench was formed, we need to point out that sometimes, the plates that make up the earth’s crust come close and collide. As the result of such collisions, one plate runs under the other one and an event called the tectonic diving.
The meaning of the diving is that the plate with the higher overall density bends down under the plate with lesser density. As the result, severe earthquakes may be experienced in the region and the depths, in which those earthquakes occur, may come close to 700 km depending on the plate size. And this Mariana Trench was formed as the result of the collision between the Pacific Plate and the Mariana Plate.
The first people ever to descent to this naturally occurred depth were the American lieutenant Donald Walsh and Swiss Scientist Jacques Piccard. They used a Bathyscaphe (A sphere shaped steel vehicle that is made out of hardened materials in order to withstand extreme pressures and that jettisons iron ballast by discharging fuel and in-taking seawater for diving) in order to make the dive. The dive itself lasted for 5 hours and they reached to a depth of 10.916 meters. In March 25, 2012; James Cameron, the director and the producer of popular films such as Titanic, Terminator, Aliens and Avatar managed to dive down to the seafloor within 156 minutes and after hours of research he conducted at this depth, he finalized his adventure with a 70 minute ascent.
Although such trips, taken down to the depths of the Mariana Trench were over with no accidents, the dangers and risks that were both faced and overlooked were also significant because at the deepest point, the pressure is 1000 times of the pressure on the surface level. The diving vehicle that James Cameron used was built to withstand to a pressure of 7250 tons per square meter. In the ocean, the pressure increases 1 kilogram in per 10 meters. That example alone explains why nobody can descent down to such low depths without any assistance and without any advanced equipment etc.