A trench is a type of excavation or depression in the ground that is generally deeper than it is wide and narrow compared with its length (as opposed to a simple hole or pit). Oceanic trenches are topographic depressions of the seafloor, relatively narrow in width but very long.
These oceanographic features are the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year.

Exploring the World’s Deepest Trenches

The ocean floor is full of dramatic landscapes, and some of the most awe-inspiring features are its deep-sea trenches. Here’s a tour of the planet’s major trenches and where they’re hidden beneath the waves:

Pacific Ocean Hotspots

• Aleutian Trench
  – Just south of Alaska’s Aleutian Islands, running westward from the Alaskan mainland.
  – It’s a hotspot for earthquakes and marks the meeting of two huge tectonic plates.
• Mariana Trench
  – In the western Pacific, east of the Mariana Islands.
  – This is the deepest spot on Earth—Challenger Deep plunges nearly 11,000 meters (36,000 feet) down!
• Japan Trench
  Off the eastern coast of Japan.
  It’s famous (and infamous) for major earthquakes and tsunamis.
• Kuril–Kamchatka Trench
  Off the Kuril Islands, northeast of Japan and near Russia’s Kamchatka Peninsula.
• Izu–Ogasawara Trench
  Southeast of Japan, near the Izu and Bonin islands.
• Ryukyu Trench
  Along the eastern edge of Japan’s Ryukyu Islands.
• Philippine Trench
  Just east of the Philippines.
• Manila Trench
  West of Luzon, Philippines.
• Yap Trench
  In the western Pacific, between the Palau Islands and the Mariana Trench.

Trenches Near Oceania and New Zealand

• Hikurangi Trench
  Just east of New Zealand’s North Island.
• Kermadec Trench
  Northeast of New Zealand, stretching towards Tonga.
• Tonga Trench
  Near the island nation of Tonga.
• Puysegur Trench
  Southwest of New Zealand.
• Hjort Trench
  Also southwest of New Zealand.
• New Hebrides Trench
  West of Vanuatu (formerly known as the New Hebrides Islands).

American Trenches

• Cayman Trench
  In the western Caribbean Sea, between Jamaica and the Cayman Islands.
• Middle America Trench
  Runs along the Pacific coast from Mexico down to Costa Rica.
• Cedros Trench (inactive)
  Off the Pacific coast of Baja California, Mexico.
• Peru–Chile Trench
  Off the Pacific coast of South America, from Peru down to Chile.

Other Notable Trenches

• Bougainville Trench
  South of New Guinea.
• Puerto Rico Trench
  – At the boundary between the Atlantic Ocean and the Caribbean Sea.
  – It’s the deepest part of the Atlantic.
• South Sandwich Trench
  East of the South Sandwich Islands, in the South Atlantic.
• Sunda Trench
  Curves from south of Java to the west of Sumatra and up toward the Andaman and Nicobar Islands.

Why Do Trenches Matter?

Ocean trenches aren’t just deep—they’re clues to how our planet works. They mark places where huge plates of the Earth’s crust crash together and one dives beneath the other, creating earthquakes, volcanoes, and sometimes even tsunamis. They’re also home to some of the most mysterious life forms on Earth, living in total darkness under crushing pressure.
Next time you look at a map of the world’s oceans, remember: some of the planet’s most dramatic landscapes are hidden far below the surface!

Some important trenches of the world

Mariana Trench

• Mariana Trench is located in the western Pacific Ocean, the Mariana 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 the oceanic lithosphere.

Tonga Trench

• Located in the southwest 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, is 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. 

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 30 km width in the east of the 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.

Kuril- Kamchatka Trench

• Another deepest part of the 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.

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 Plate, the Kermadec Trench has a maximum depth of 1o.04 km.

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 the 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.

Japan Trench

• Another deep submarine trench located east of the Japanese islands, the Japan trench 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 lead to the movement on the subduction zone with the Japan Trench.

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.

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.

Peru–Chile Trench

• The Atacama Trench was formed as a result of a convergent boundary, between the subducting Nazca and the South American Plates.
• 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.