The oceans and seas surrounding the continents offer a number of wonders, many of which are yet to be discovered by humans. The vast bodies of water that covers over 70% of the planet’s surface, holding around 1.35 billion cubic kilometres of water, has plateaus, valleys, plains, mountains, and trenches on its basin just as they are on the surface layer of the Earth.
And, interestingly, the underwater mountains, plains etc. are huge in size compared to those on the dry land.
The mountains that are situated on the ocean basin are higher than those we see on land, and similarly, the plains are flatter and so the trenches are much deeper.
Among all the features that oceans offer, it’s the very depth of these water bodies that makes them so enchanting. Indeed, the ocean is deep and the average depth of the oceans and seas surrounding the continents is around 3.5km.
In fact, the part of the ocean that is deeper than just 200 meters is considered to be the “deep sea.” However, some part of the oceans is going up to depths of several kilometres. But what is the deepest part of the ocean exactly?
Scientifically speaking, the deepest part of the ocean refers to the maximum depth of a point that can be accessed or defined. Every such deepest part of the ocean is referred to as deep trenches.
Known as the hadal zone, the very bottom of the deepest sea trench is a result of plunging trenches created by shifting tectonic plates.
Currently, there are 46 hadal habitats across the oceans and humans know very little about these regions since it’s very difficult to study these parts of the oceans. Here is a list of ten such points that mark the deepest points of oceans.
1. Mariana Trench
Located in the western Pacific Ocean, the Marina Trench is considered to be the deepest part of the Earth’s surface. In fact, it is the Challenger Deep in the Mariana Trench that is known as the deepest point.
Appears as a crescent-shaped scar, the trench measures around 2,550 km long, 69 km wide on average and has a maximum depth of 10.91 km at the Challenger Deep. At the same time, some other efforts measured the deepest portion at 11.034 km.
The deep holes in the Mariana trench were formed due to the collision of converging plates of oceanic lithosphere. During the collision, one plate descends into the mantle and the downward flexure forms a trough at the line of contact between the plates.
At the bottom of the Marina Trench, the density of water is increased by 4.96% due to the high pressure at the seabed. However, the expeditions conducted at various times have observed the presence of large creatures such as a flatfish, large shrimp, huge crustaceans and even an unidentified type of snailfish.
2. Tonga Trench
Located in the south-west Pacific Ocean and at the Kermadec Tonga Subduction Zone’s northern end, the Tonga Trench lies around 10.882 km below sea level. The deepest point in the Tonga trench, known as the Horizon Deep, considered to be the second deepest point on earth after the Challenger Deep and the deepest trench of the Southern Hemisphere.
Stretches at a distance of 2,500 km from New Zealand’s North Island northeast to the island of Tonga, the Tonga trench was formed due to the subduction of the Pacific plate by the Tonga plate.
Researchers have also found that these plate movements also cause large volcanoes in the Japan trench as well as the Mariana trench. According to marine scientists, the sediments of the Horizon Deep houses a community of roundworms.
3. Philippine Trench
The third deepest point in the world, the Galathea Depth in the Philippine trench is 10.54 km below sea level. Also known as Mindanao Trench, this submarine trench is located in the Philippine Sea, spreads in a length of 1,320km and 30km width in the east of Philippines.
Prominent among other trenches in the Philippine Sea, this trench was formed due to a collision between the Eurasian plate and the smaller Philippine plate. The other major trenches in the Philippine sea include Manila Trench East Luzon Trench, Negros Trench, Sulu Trench and Cotabato Trench.
It is said that the scientists considered the Philippine Trench as the planet’s deepest point until 1970. According to scientists, the Philippine trench is younger than 8-9 million years ago.
4. Kuril- Kamchatka Trench
Another deepest part of ocean belonging to the Pacific Ocean, this trench lies at a considerable depth of 10.5 km below sea level. Lying close to Kuril Island and off the coast of Kamchatka, this trench is responsible for a number of oceans bed volcanic activities in the region.
The trench was formed due to the subduction zone that was developed in the late Cretaceous, which created the Kuril island and the Kamchatka volcanic arcs.
5. Kermadec Trench
Another submarine trench lies on the floor of the South Pacific Ocean, the Kermadec Trench stretches around 1,000 km between the Louisville Seamount Chain and the Hikurangi Plateau.
Formed by the subduction of the Pacific plate under the Indo-Australian Plat, the Kermadec Trench has a maximum depth of 1o.04 km.
Along with the Tonga Trench to the north, the Kermadec Trench creates the 2,000 km-long, near-linear Kermadec-Tonga subduction system.
The trench is also home for a variety of species including a species of giant amphipod, measures approximately 34 cm in length, at the bottom of the trench. A few years ago, the Kermadec Trench was in news after the Nereus, an unmanned research submarine, imploded because of the high pressure at a depth of 9,990 meters while conducting explorations at the Kermadec Trench.
6. Izu-Ogasawara Trench
Located in the western Pacific Ocean, the Izu-Ogasawara Trench has a maximum depth of 9.78km. Also known as Izu-Bonin Trench, this deep trench stretches from Japan to the northern section of Mariana Trench and it is also an extension of the Japan Trench. Apart from the Izu-Ogasawara Trench, the western Pacific Ocean houses the Izu Trench and the Bonin Trench.
7. Japan Trench
Another deep submarine trench located east of the Japanese islands, Japan trench (as shown in image above) is part of the Pacific Ring of Fire in the northern Pacific Ocean. With a maximum depth of 9 km, the Japan trench stretches from the Kuril Islands to the Bonin Islands and is also the extension of the Kuril-Kamchatka Trench and the Izu-Ogasawara Trench to the north and south respectively.
The trench was formed due to the subduction of the oceanic Pacific plate beneath the continental Okhotsk Plate. And, it’s the tsunamis and earthquakes that leads to the movement on the subduction zone with the Japan Trench.
8. Puerto Rico Trench
Located between the Caribbean Sea and the Atlantic Ocean, the Puerto Rico trench marks the deepest point in this region and the eighth deepest point found on the earth’s surface.
Lies at a depth of 8.64 km, spotted at Milwaukee Deep and measures a length of over 800 km, this trench has been responsible for many tragic tsunamis and earthquake activities in this region.
Efforts for complete mapping of this trench have been undergoing on for a quite long time now. It was the French bathyscaphe Archimède who first attempted to explore the seafloor in 1964 and a robotic vehicle was sent to the trench in 2012 to study the characteristics of the trench.
9. South Sandwich Trench
The deepest trench in the Atlantic Ocean after Puerto Rico Trench, South Sandwich Trench is at a depth of about 8.42 km, described as Meteor Deep and runs for over 956 km, making it one of the most noticeable trenches of the world.
Located 100 km to the east of the South Sandwich Islands in the southern Atlantic Ocean, this trench was formed by the subduction of the South American Plate’s southernmost portion beneath the small South Sandwich Plate. This South Sandwich Trench is also associated with an active volcanic arc.
10. Peru–Chile Trench
The Peru–Chile Trench (the Atacama Trench) is located around 160 km off the coast of Peru and Chile in the eastern Pacific Ocean. The Atacama Trench has a maximum depth of 8.06 km below sea level. The deepest point of the trench is known as Richards Deep.
The trench measures around 5,900 km in length and 64 km in mean width while it covers an area of about 590,000 square kilometres. The Atacama Trench was formed as a result of a convergent boundary, between the subducting Nazca and the South American Plates.
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