The vast world’s oceans hold unprecedented mysteries, among them being deep trenches. Ocean beds have valleys, plateaus, flatlands, and mountains, similar to the earth’s surface. Such features have led to the deepness of the world’s oceans, most of which haven’t been explored. The trenches are created when shifting tectonic plates slip below other plates.
These depths go up to several kilometers as the underwater features are believed to be more enormous than what we see on land. Areas that go more than 200 meters or about 100 fathoms deep are categorized as the deep sea.
How Are Ocean Trenches Formed?
Ocean trenches are formed by the subduction process where tectonic plates converge. It may involve two or more plates, and the denser plate is subducted beneath the lighter one. This leads to the bending of the seafloor and the lithosphere, creating a long and narrow V-shaped depression.
The oceans are the deepest in the world and are located in every ocean basin worldwide. Ocean trenches are located in the hadalpelagic zone, the deepest layer of the ocean. The aura in the ocean trenches is composed of minimal or no sunlight, intense pressure, and frigid temperatures. However, some unique species still thrive in the deepest parts of the ocean.
The deepest point in the ocean is the maximum depth that can be defined, and here are the ten deepest points of the world’s oceans.
1. Mariana Trench (Challenger Deep)
The trench is located in the western Pacific, between Australia and Japan, and runs to a depth of 10.91 km below sea level. Mt. Everest has an approximate height of 8,850, yet it is the tallest mountain in the world. Such comparisons make Mariana Trench the deepest point of the ocean and the deepest point on earth. It has a crescent shape which runs for 2,550 kilometers and is 69 kilometers wide.
Its occurrence is because of the numerous tectonic plates converging that have also led to the formation of deep holes. High pressure from the seabed causes the water density at the bottom of the trench to increase by 5%, in addition, to increasing of density of saltwater compared to freshwater that we discussed in this article.
Despite such intense conditions, several marine creatures, such as flatfish, large crustaceans, shrimps, and snailfish, have been discovered.
While many people have climbed to the top of Mt. Everest, only two people are believed to have reached the deepest part of the Challenger Deep. According to scientists, further exploration will lead to the discovery of new marine species in the Mariana Trench.
2. Tonga Trench
The Pacific again seems full of wonders, with Tonga Trench located in the southwest part of the ocean. Tonga Trench’s deepest point is approximately 10.88 km below sea level and is the deepest in the Southern Hemisphere. It lies on a 2,500 km distance with a width of about 80 km and stretches from New Zealand’s North Island to the islands of Tonga.
Tonga Trench formed due to tectonic plate movements that led to a series of volcanoes. Scientists state that the plate movements caused the Pacific plate subduction by the Tonga plate. The deepest point in this tremendous trench is called Horizon Deep.
Horizon Deep is one of the most dramatic deep ever seen, as it has profound slopes and ridges that are relatively steeper. Tonga Trench is only 300 feet shallower than the Challenger Deep, and the water temperatures are approximately 1.1 degrees Celsius.
3. Philippine Trench
Also known as the Mindanao Trench, its location is in the Philippine Sea and is 10.54 km in depth below sea level. The Philippine Trench covers 30 km in width, 1,320 km in length and is the most renowned trenches located in the Philippine Sea. Its formation resulted from the Eurasian Plate collision with the smaller Philippine Plate.
The trench’s prominence is also because it was known to be the deepest trench by the 1970s. In addition, it is the deepest compared to surrounding trenches, such as Negros Trench, the Manila Trench, Sulu Trench, and Cotabato Trench. Its deepest spot is called the Galathea Depth.
After the collision, the ocean bed formed a series of folds and faults emerging above the surface. Some of these seamounts are volcanic, and scientists claim that Philippine Trench is one of the youngest and is 8 to 9 million years of age. The trench is also prominent for the vast array of earthquakes that occur.
4. Kuril-Kamchatka Trench
Another spot in the western Pacific Ocean is the Kuril-Kamchatka which has a depth of 10.5 km below sea level. It lies close to Kuril Island and contributes to a huge portion of the ocean and volcanic activities in the area. Its formation resulted from a subduction zone created in the last years of the Cretaceous period. This also led to the emergence of Kuril Island and the Kamchatka arcs.
This trench has steep slopes that appear in a series of terraces and steps. Its intense volcanism is due to the subduction of the pacific plate under the Okhotsk Plate. Kuril-Kamchatka is the second largest area of hadal habitat.
5. Kermadec Trench
Kermadec Trench is situated in the South of the Pacific Ocean, and its deepest point is 10.04 km below sea level. It is a 1000 km stretch from the Louisville Seamount Chain to the Hikurangi Plateau. The trench is also responsible for creating the Kermadec-Tonga subduction system, which is 2,000 km long and is far from any larger landmass.
The formation of the Kermadec Trench results from the Pacific Plate subduction beneath the Indo-Australian Plate. The trench has become a habitat to numerous species, such as the giant amphipod, hadal snailfish, and pearlfish, while another interesting marine life is still under exploration. Other creatures survive in extreme conditions in the trench, like deep-sea bacteria, worms, corals, shrimps, and mussels.
New Zealand’s government approved the establishment of a sea sanctuary in 2016 that focuses on the trench. This could be the largest marine no-take zone worldwide if such plans are executed.
6. Izu-Ogasawara Trench
Also known as the Izu-Bonin Trench, the deepest point in the trench has a depth of 9.78 km below sea level. It is situated in the western Pacific Ocean and extends all the way from Japan to the Northern region of the Mariana Trench. The Izu-Bonin Trench formed after the subduction of the Pacific Plate below the Philippine Sea Plate. This activity also led to the formation of the Bonin and Izu Islands.
Izu-Bonin Trench is an extension of the Japan Trench. The trench has three subdivisions, the landward, the trench floor, and the seaward wall, and they are arranged from west to east. The long trench has several unique species which have evolved independently as they do not mingle with other waters.
7. Japan Trench
The trench lies east of Japanese islands in the western North Pacific Ocean. Japan Trench is situated between the Bonin and Kuril Islands, and its formation resulted in a series of depressions between the area. It was formed due to the subduction of the Pacific Plate below the Okhotsk Plate.
Japan’s Trench is part of the Pacific Ring of Fire, and its deepest point is approximately 9 km below sea level. This region around northern Japan is famous for tsunamis and earthquakes due to the continuous movements of the subduction zone. Numerous people have executed various explorations in the trench. Discoveries such as the snailfish at a depth of 7,700 meters were unleashed in 2008.
By then, this was the deepest-ever living fish to be filmed. An exploration broke the record in the Marina Trench in May 2017 that captured an unrecognized type of snailfish at a depth of 8,178 meters.
8. Puerto Rico Trench
It’s the eighth deepest point in the world’s ocean trenches and is situated between the Caribbean Sea and the Atlantic Ocean. Puerto Rico is the deepest trench in this region and has a length of 800 km and above and an 8.64 km depth below sea level. It is a major contributor to the tsunamis and earthquakes that have been witnessed in this area.
The trench was first explored in 1964, and its maximum depth is at Milwaukee Deep. It also marks the deepest point in the Atlantic Ocean. Its formation is due to the subduction of the North American Plate beneath the smaller Caribbean Plate. The scarping between the North American and Caribbean plates led to the formation of a large transform fault.
Puerto Rico is 250 kilometers long and is viewed as a very level depression. Other explorations led to the discovery of a mud volcano at 7.9 kilometers below sea level. Its southern side, located north of Puerto Rico, has a smooth layer of limestone.
9. South Sandwich Trench
With a depth of 8.42 km below sea level, South Sandwich is a trench that is the second deepest after Puerto Rico in the Atlantic Ocean. This trench stretches a distance of 956 kilometers, and its deepest part is called the Meteor Deep. This point was discovered during the German Meteor expedition, and it was named after the German survey ship Meteor.
Its formation occurred after the subduction of the South American Plate subducted beneath the small South Sandwich Plate. It also led to the creation of the active volcanic arc. South Sandwich Trench is 100 km off the eastern coast of the Sandwich Islands and is the deepest in the Southern Atlantic Ocean. The complex trench hosts a variety of uncommon species, such as scavenging amphipods, snailfish, stalked crinoids, and brittle stars.
10. Peru-Chile Trench
Also known as Atacama Trench, its maximum depth is 8.06 km below sea level. This trench is situated 160 km off the coast of Chile and Peru. It lies on the ocean bed of the eastern Pacific Ocean, and the deepest spot in the trench is referred to as “Richards Deep.”
The trench has a length of about 5,900 km, and 64 km width and lies on an area of 590 thousand square kilometers. Its formation was due to the geologically formed convergent boundary between the Nazca Plate and South American Plate.
The Nazca Plate is subducted beneath the South American Plate, where two seamount ridges from the Nazca plate enter the subduction zone. Three new snailfish species were identified in the depth of the Peru-Chile Trench. Numerous earthquakes have been witnessed in the area and have led to various landslides and tsunamis.
The ocean waters are quite scary but fascinating to explore. Although there are numerous things to explore in the waters, ocean trenches remain one of the mysterious wonders. They are formed because of the subduction of tectonic plates, leading to deep trenches. The collision between plates also leads to forming other features, such as islands, volcanoes, and plateaus.
Exploration of these complex trenches reveals uncommon species such as snailfish, amphipods, crinoids, and mussels, to name a few. The above post has articulated the ten top deepest ocean trenches, how they were formed, and what they contain.