The deepest ocean trench on Earth, the Mariana Trench (also known as the Marianas Trench) is located in the Western Pacific Ocean, just southeast of the Mariana Islands near Guam. Because the Mariana Islands are a U.S. Commonwealth and Guam is a U.S. territory, the trench falls under the United States jurisdiction; and, in 2009, the 195,000 square mile area surrounding the islands was established by President George W. Bush as a protected marine reserve called the Mariana Trench Marine National Monument.
The trench is 1,580 miles long, which is more than five times the length of the Grand Canyon, and forty-three miles wide. The depth, however, is a bit more difficult to ascertain. The trench was first discovered in 1875 by the HMS Challenger, which used recently invented sounding equipment to estimate a depth of 26,850 feet near the southern end of the trench. In 1899, Nero Deep was discovered with a depth of 31,693 feet. That remained the deepest reading until thirty years later when a hole with a depth of 32,197 feet was discovered. The deepest point of the trench is Challenger Deep, named for the Challenger expedition, which is over 36,000 feet deep. The second deepest point, Sirena Deep, is located 124 miles east of Challenger Deep and has a depth of 35,462. The highest point on Earth, Mount Everest, is 29,026 feet tall, meaning that the entire mountain could fit inside either of these two points in the Marianas Trench and still be underwater.
Like Mount Everest, the Mariana Trench presents a challenge to those desiring to reach its most extreme point, though there have been far more voyages to the tip of Mount Everest than there have been to the bottom of Challenger Deep. However, it has been done. The first descent occurred on January 23, 1960. The French-built vessel, Bathyscaphe Trieste, was manned by United States Navy Lieutenant, Don Walsh and Swiss scientist, Jacques Piccard, who designed the bathyscaphe along with his father, Auguste Piccard. The vessel reached a depth of 35,814 feet. Since then, there have been two unmanned vessels sent into the trench to gather data – the Japanese submarine, Kaiko, in 1995 and the U.S. hybrid vehicle, Nereus, in 2009. In 2012, the filmmaker James Cameron launched the second manned descent into the trench, piloting the Deepsea Challenger to a depth of 35,756 feet.
Despite an atmospheric pressure one thousand times that at sea level, the Mariana Trench is home to a variety of marine life. These sea creatures are able to survive in complete darkness and withstand a pressure that is the equivalent of having fifty jumbo jets piled on top of you. Because of its distance from land, food such as plankton and vegetation is scarce. As a result, bacteria subsist on chemicals, like methane and sulfur, which are emitted from the crust. Other life forms feed on the bacteria as well as on “marine snow,” which is debris from the decomposition of the marine life above. “Whale fall,” the name given to the debris from the decomposition of whales, is a significant source of nutrition for marine life in the deep.
The most common creatures of the Mariana Trench are xenophyophores, amphipods, and holothurians. Xenophyophores are single-celled organisms that absorb their food and have the appearance of giant amoebas. Amphipods, on the other hand, are more closely related to shrimp and are the scavengers of the deep. Holothurians seem to be translucent sea cucumbers. In 2017, a new organism was discovered and named the Mariana snailfish. Despite the diminutive appearance of its pink, scale-less body, the snailfish is one of the most dominant predators of the Mariana Trench. It lives at a depth of 26,200 feet, surviving at a depth lower than any other fish, and feeds off the various invertebrates inhabiting the trench.
In addition to the strange marine life in the trench, there are also strange volcanoes there. The Mariana Islands were actually formed by a chain of volcanoes which rises above the surface of the ocean. Those volcanoes exist beneath the surface as well. One of these submarine volcanoes, Eifuku, emits liquid carbon dioxide from the hydrothermal vents, which resemble chimneys, at a temperature of 217 degrees Fahrenheit. Another submarine volcano, Daikoku, has a pool of molten sulfur 1,345 feet below the surface of the ocean. The Mariana Trench is the only place on Earth where something like that exists.