In our world today, oceans cover more than 70% of the surface of our planet. Water is quite abundant. In some of these oceans, lie trenches. Trenches define the deepest areas in our world’s oceans. Oceanic trenches are narrow, V-shaped, topographic depressions on the ocean floor. They are also the feature of convergent plate boundaries, specifically at subduction zones. Trenches mark the position at which a subducting plate begins to descend under another plate. Most often, trenches are parallel to volcanic arcs such like the Izu-Bonin-Mariana arc (ScienceDaily). The Izu-Bonin-Mariana arc system is composed of volcanic islands. These were created by the subduction of tectonic plates. In addition to the many volcanoes that exist here, the most interesting volcanoes are the underwater volcanoes. For example, the Eifuku submarine volcano emits liquid carbon dioxide through hydrothermal vents. These can get up to over 200 degrees Fahrenheit (Oskin).
Although, there are many trenches that descend far beneath our world’s oceans, there is only one that can be seen as the deepest. The Mariana Trench.
The Mariana Trench contains the deepest area in the Pacific Ocean. It is also the deepest area on our planet. It is located east of the Mariana Islands and is part of the western Pacific system of oceanic trenches. It coincides with an oceanic-oceanic convergent plate boundary. It is also located near the subduction zone. The Mariana Trench is the result of the oceanic Pacific plate which is being subducted beneath another oceanic plate, known as the Mariana plate. This is because the Pacific plate is older and more dense (Britannica). At subduction zones, such as by the Mariana Trench, the dense crust sinks back into the mantle. This results in the destruction of rock. The trench stretches a vast 1,580 miles long and is only 43 miles wide. It has a maximum depth of approximately 36,210 feet and the deepest area is known as the Challenger Deep (Oskin). Interestingly, the water pressure at the bottom of the Mariana Trench is about 15,750 psi. Compared to the pressure where we live, the pressure at the bottom of the trench is almost 1,000 times bigger. This means that without adequate technological equipment, a person will be crushed to death under that much pressure (Agustina). The temperature at the bottom of the Mariana Trench is about 36 degrees Fahrenheit. The deeper into the ocean you go, the colder it is supposed to get. The temperature at the bottom of the Mariana Trench is slightly warmer than usual because of hydrothermal vents. The vents are formed from tectonic plates that are spreading which release high amounts of hydrogen sulfide (Agustina).
It is extremely difficult for living creatures to exist at such depths because of the immense pressure. Therefore, most of the life in the Mariana Trench is microbial in nature. Many bacteria are able to survive because they feed off the methane and sulfur. Those gases are emitted from the crust of our Earth (NOAA). The Pyrococcus CH1 is one example of an extremophilic microorganism that is able to withstand the pressures deep down (DailyGalaxy). The study of extremophilic organisms is providing NASA with ideas of what life could be like on the moons of Jupiter (DailyGalaxy). The anglerfish is a good example of how pressure, lack of sunlight, and temperatures affect the development of living creatures. Furthermore, life in the deep is extremely difficult for other living creatures also. For example, the dragonfish is able to produce its own light in order to catch small prey. The hatchet fish has adapted by evolving giant eyes in order to see their prey. Interestingly, some creatures are translucent because it is a way for them to stay hidden and avoided from prey. Some creatures are also red. Being translucent or red absorbs any blue light that has made its way down to the depths of the deep ocean (Starkey).
The Mariana Trench was first discovered in 1951 by British Survey ship, Challenger II. This is how the Challenger Deep got its name. The Survey ship used echo-sound methods and discovered depths of up to almost seven and a half miles (Britannica). The sound waves method was a good method to measure the depth, but not good at seeing what lies at the bottom of the trench. In 1960, the first humans descended down into the Challenger Deep. Ocean Engineer Jacques Piccard and Navy Lt. Don Walsh both made a trip down. Using a U.S. Navy submersible bathyscaphe, they made a five hour descend to the bottom. They reached a maximum depth of 35,814 feet. They spent only 20 minutes down there, but when they turned on the floodlights, Piccard claims to have seen a flatfish (resemblance to a flounder). Pictures were near impossible due to the stirred up silt from the bathyscaphe. This was a profound discovery, given that many researchers thought life could not exist at these depths (Britannica). In 1995, a lesser-known expedition took place with a Japanese unmanned submarine, Kaiko. They discovered various marine life such as shrimps and sand worms. They used a sophisticated submersible device that was able to withstand the immense pressures of the deep sea. They took a mud sample and found over 200 different microorganisms in existence in the Mariana Trench (JAMSTEC). In 2012, film Director, James Cameron descended to the bottom of the Mariana Trench to the Challenger Deep. He reached an incredible depth of 35,756 feet. However, Piccard and Walsh descended to an even lower depth of 35,814 feet. Cameron used the Deep sea Challenger submarine and recorded what he saw. As Cameron stared out the small window of the submarine, all he saw was the black abyss. A lonely, cold, isolated, black and barren abyss. Although Cameron did not see anything worth noting, he did appreciate the nothingness exhibited by the Challenger Deep. Interestingly, the pressure was so great at this depth, that it shrunk Cameron’s submarine by over three inches (Than). There have not been many explorations at this depth. The only two known cases where humans descended down to depths this great are exemplified by Cameron, Piccard and Walsh. Some unmanned missions were attempted, but there is still much unknown as to what lies deep within the Mariana Trench.
In 2009, the Mariana Trench was named a national monument. President George W. Bush created the Mariana Trench Marine National Monument (MTMNM) which resulted in the creation of a protected marine reserve for almost the entirety of the trench, the Mariana Islands, and any other waters surrounding it. It is protected for about 195,000 square miles. President Bush was able to deem the Mariana Islands and surrounding waters a National Monument because the Mariana Islands are part of the U.S. Commonwealth. This means that the U.S. has complete jurisdiction over the Mariana Islands, which includes the Mariana Trench (Oskin).
Research into the depths of the Mariana Trench is extremely difficult. Due to the pressure, temperature and depth, most submarines are unable to withstand the pressures. With such limited access to depths beyond 20,000 feet, research is seldom conducted (Drazen). Through the various expeditions that have been attempted, we now know that some life exists at the bottom of the trench. Although, the life existing is mainly microorganisms, the other living creatures that exist have evolved very peculiarly. It would have been interesting to see a picture of the fish Piccard claimed to have seen. We now know that deep sea volcanoes, hydrothermal vents and the existence of bacteria are present, deep within the Mariana Trench. In our world today, we know more about outer space than we do about the deep, dark depths of our oceans, which comprise over 70 percent of our planet. Given the time and patience, one day, researchers will be able to develop larger pressure-resistant technology that will allow those researchers to study what exists at the bottom of the Mariana Trench.