# List of submarine topographical features

This is a list of submarine topographical features, oceanic landforms and topographic elements.

## Abyssal plain

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 meters (9,800 ft) and 6,000 meters (20,000 ft). Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains are among the flattest, smoothest and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone. Abyssal plains cover more than 33% of the ocean floor (about 23% of Earth's surface), but they are poorly preserved in the sedimentary record because they tend to be consumed by the subduction process.
The abyssal plain is formed when the lower oceanic crust is melted and forced upwards by the asthenosphere layer of the upper mantle. As this basaltic material reaches the surface at mid-ocean ridges, it forms new oceanic crust. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited from turbidity currents that have been channeled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment is composed chiefly of pelagic sediments.
Use of a continuously recording fathometer enabled Tolstoy & Ewing in the summer of 1947 to identify and describe the first abyssal plain. This plain, located to the south of Newfoundland, is now known as the Sohm Abyssal Plain. Following this discovery many other examples were found in all the oceans.

### List of abyssal plains and oceanic basins

Following is a list of named abyssal plains and oceanic basins:
| Name | Alternate name | Ocean | Coordinates |
| Adriatic Abyssal Plain | (Adriatic Basin) | Mediterranean | 43°0′N 15°0′E﻿ / ﻿43.000°N 15.000°E﻿ / 43.000; 15.000 |
| Agulhas Bank | (Agulhas Basin) | South Atlantic Ocean | 35°30′S 21°00′E﻿ / ﻿35.500°S 21.000°E﻿ / -35.500; 21.000 |
| Alaska Plain | (Alaskan Abyssal Plain, Alaskan Plain) | North Pacific Ocean | 55°0′N 143°0′W﻿ / ﻿55.000°N 143.000°W﻿ / 55.000; -143.000 |
| Alborán Plain | (Alboran Abyssal Plain) | Alboran Sea (Mediterranean Sea) | 35°55′N 3°50′W﻿ / ﻿35.917°N 3.833°W﻿ / 35.917; -3.833 |
| Aleutian Basin | (Aleutskaya Kotlovina, Bering Abyssal Plain, Bering Basin, Bering Sea Basin) | North Pacific Ocean | 57°0′N 177°0′E﻿ / ﻿57.000°N 177.000°E﻿ / 57.000; 177.000 |
| Amerasia Basin | (Central Polar Basin; consists of the Canada Basin and the Makarov Basin) | | |
| Amundsen Basin | (Amundsen Basin) | Arctic Ocean | 89°0′N 80°0′E﻿ / ﻿89.000°N 80.000°E﻿ / 89.000; 80.000 |
| Amundsen Plain | (Amundsen Abyssal Plain) | Southern Ocean | 65°0′S 125°0′W﻿ / ﻿65.000°S 125.000°W﻿ / -65.000; -125.000 |
| Angola Plain | (Angola Abyssal Plain, Angola Basin) | South Atlantic Ocean | 15°0′S 2°0′E﻿ / ﻿15.000°S 2.000°E﻿ / -15.000; 2.000 |
| Argentine Abyssal Plain | (Argentine Plain, Argentine Basin) | South Atlantic Ocean | 47°30′S 50°0′W﻿ / ﻿47.500°S 50.000°W﻿ / -47.500; -50.000 |
| Atlantic-Indian Basin | | Indian Ocean | 60°0′S 15°0′E﻿ / ﻿60.000°S 15.000°E﻿ / -60.000; 15.000 |
| Balearic Abyssal Plain | | Mediterranean Sea | 40°00′N 01°30′E﻿ / ﻿40.000°N 1.500°E﻿ / 40.000; 1.500 |
| Baffin Basin | (Baffin Bay Basin) | North Atlantic Ocean | 73°15′N 67°0′W﻿ / ﻿73.250°N 67.000°W﻿ / 73.250; -67.000 |
| Barracuda Plain | (Barracuda Abyssal Plain) | North Atlantic Ocean | 17°0′N 56°30′W﻿ / ﻿17.000°N 56.500°W﻿ / 17.000; -56.500 |
| Bauer Basin | | | |
| Bellingshausen Plain | (Bellingshausen Abyssal Plain) | Southern Ocean | 64°0′S 90°0′W﻿ / ﻿64.000°S 90.000°W﻿ / -64.000; -90.000 |
| Biscay Plain | (Biscay Abyssal Plain) | North Atlantic Ocean | 45°0′N 7°15′W﻿ / ﻿45.000°N 7.250°W﻿ / 45.000; -7.250 |
| Blake Basin | (Blake Abyssal Plain) | North Atlantic Ocean | 29°30′N 76°4′W﻿ / ﻿29.500°N 76.067°W﻿ / 29.500; -76.067 |
| Boreas Plain | (Boreas Abyssal Plain) | Arctic Ocean | 77°0′N 1°0′E﻿ / ﻿77.000°N 1.000°E﻿ / 77.000; 1.000 |
| Burdwood Abyssal Plain | | South Atlantic Ocean | |
| Canada Plain | (Canada Abyssal Plain, Canada Basin, Canada Deep, Canadian Plain, Kanadskaya Abissal'naya Ravnina Kanadskaya). One of two sub-basins of the Amerasia Basin. | Arctic Ocean | 80°0′N 140°0′W﻿ / ﻿80.000°N 140.000°W﻿ / 80.000; -140.000 |
| Canary Basin | | | |
| Cape Plain | (Cape Abyssal Plain, Cape Basin) | South Atlantic Ocean | 34°45′S 6°0′E﻿ / ﻿34.750°S 6.000°E﻿ / -34.750; 6.000 |
| Cape Verde Plain | (Cape Verde Abyssal Plain) | North Atlantic Ocean | 23°0′N 26°0′W﻿ / ﻿23.000°N 26.000°W﻿ / 23.000; -26.000 |
| Cascadia Plain | (Cascadia Abyssal Plain, Cascadia Basin, Bassin Cascadia, Great Trough) | North Pacific Ocean | 47°0′N 127°30′W﻿ / ﻿47.000°N 127.500°W﻿ / 47.000; -127.500 |
| Ceará Plain | (Brazil Basin, Ceara Abyssal Plain) | North Atlantic Ocean | 0°0′N 36°30′W﻿ / ﻿0.000°N 36.500°W﻿ / 0.000; -36.500 |
| Central Pacific Basin | | | |
| Ceylon Plain | (Ceylon Abyssal Plain) | Indian Ocean | 4°0′S 82°0′E﻿ / ﻿4.000°S 82.000°E﻿ / -4.000; 82.000 |
| Chile Basin | | | |
| Chukchi Plain | (Chukchi Abyssal Plain) | Arctic Ocean | 77°0′N 172°0′W﻿ / ﻿77.000°N 172.000°W﻿ / 77.000; -172.000 |
| Cocos Abyssal Plain | (Cocos Basin) | Indian Ocean | |
| Colombian Plain | (Colombia Abyssal Plain, Colombian Abyssal Plain) | Caribbean (Atlantic Ocean) | 13°0′N 76°0′W﻿ / ﻿13.000°N 76.000°W﻿ / 13.000; -76.000 |
| Comoro Plain | (Comores Abyssal Plain) | Mozambique Channel (Indian Ocean) | 13°45′S 44°30′E﻿ / ﻿13.750°S 44.500°E﻿ / -13.750; 44.500 |
| Cuvier Plain | (Cuvier Abyssal Plain) | Indian Ocean | 22°0′S 111°0′E﻿ / ﻿22.000°S 111.000°E﻿ / -22.000; 111.000 |
| Demerara Plain | (Demerara Abyssal Plain) | North Atlantic Ocean | 10°0′N 48°0′W﻿ / ﻿10.000°N 48.000°W﻿ / 10.000; -48.000 |
| Dibble Basin | | Southern Ocean | 65°20′S 133°0′E﻿ / ﻿65.333°S 133.000°E﻿ / -65.333; 133.000 |
| Dumshaf Plain | (Dumshaf Abyssal Plain) | Arctic Ocean | 68°0′N 5°0′E﻿ / ﻿68.000°N 5.000°E﻿ / 68.000; 5.000 |
| Enderby Plain | (Enderby Abyssal Plain, East Abyssal Plain) | Southern Ocean | 60°0′S 40°0′E﻿ / ﻿60.000°S 40.000°E﻿ / -60.000; 40.000 |
| Eratosthenes Abyssal Plain | (Eratosthenes Seamount) | Mediterranean Sea | 33°40′N 32°40′E﻿ / ﻿33.667°N 32.667°E﻿ / 33.667; 32.667 |
| Eurasian Basin | (Norway Abyssal Plain, Norwegian Basin; consists of the Amundsen Basin and the Nansen Basin) | Arctic Ocean | 80°N 90°E﻿ / ﻿80°N 90°E﻿ / 80; 90 |
| Euxine Abyssal Plain | | Black Sea | |
| Fernando de Noronha Plain | (Fernando de Noronha Abyssal Plain, Planicie Abissal de Fernando de Noronha) | South Atlantic Ocean | 3°0′S 31°0′W﻿ / ﻿3.000°S 31.000°W﻿ / -3.000; -31.000 |
| Ferradura Plain | (Ferradura Abyssal Plain, Planicie Abissal da Ferradura) | North Atlantic Ocean | 36°0′N 10°45′W﻿ / ﻿36.000°N 10.750°W﻿ / 36.000; -10.750 |
| Fletcher Plain | (Abissal’naya Ravnina Fletchera) | Arctic Ocean | 86°0′N 179°59′W﻿ / ﻿86.000°N 179.983°W﻿ / 86.000; -179.983 |
| Florida Plain | (Florida Abyssal Plain) | Gulf of Mexico (Atlantic Ocean) | 25°30′N 86°0′W﻿ / ﻿25.500°N 86.000°W﻿ / 25.500; -86.000 |
| Fram Basin | (Barents Abyssal Plain, Barents Plain) One of two sub-basins of the Eurasian Basin. | Arctic Ocean | 83°0′N 35°0′E﻿ / ﻿83.000°N 35.000°E﻿ / 83.000; 35.000 |
| Gambia Plain | (Gambia Abyssal Plain, Gambia Basin) | North Atlantic Ocean | 12°0′N 28°0′W﻿ / ﻿12.000°N 28.000°W﻿ / 12.000; -28.000 |
| Gascoyne Plain | (Exmouth Abyssal Plain, Gascogne Plain, Gascoyne Abyssal Plain) | Indian Ocean | 16°0′S 110°0′E﻿ / ﻿16.000°S 110.000°E﻿ / -16.000; 110.000 |
| Greenland Plain | (Greenland Abyssal Plain, Iceland Basin, Plaine du Groenland) | Arctic Ocean | 75°0′N 3°0′W﻿ / ﻿75.000°N 3.000°W﻿ / 75.000; -3.000 |
| Grenada Abyssal Plain | | Caribbean Sea (Atlantic Ocean) | |
| Guiana Basin | | | |
| Guinea Plain | (Guinea Abyssal Plain) | North Atlantic Ocean | 1°0′N 3°0′W﻿ / ﻿1.000°N 3.000°W﻿ / 1.000; -3.000 |
| Hatteras Plain | (Hatteras Abyssal Plain) | North Atlantic Ocean | 31°0′N 71°0′W﻿ / ﻿31.000°N 71.000°W﻿ / 31.000; -71.000 |
| Herodotus Basin | (Herodotus Abyssal Plain, Herodotus Plain) | Levantine Sea (Mediterranean Sea) | 33°0′N 28°0′E﻿ / ﻿33.000°N 28.000°E﻿ / 33.000; 28.000 |
| Hellenic Trench | (Metapan Deep System) | Ionian Sea | 36°23′N 22°38′E﻿ / ﻿36.383°N 22.633°E﻿ / 36.383; 22.633 |
| Hispaniola Plain | (Hispaniola Abyssal Plain) | North Atlantic Ocean | 20°18′N 71°35′W﻿ / ﻿20.300°N 71.583°W﻿ / 20.300; -71.583 |
| Horseshoe Plain | (Horseshoe Abyssal Plain) | North Atlantic Ocean | 35°40′N 12°20′W﻿ / ﻿35.667°N 12.333°W﻿ / 35.667; -12.333 |
| Iberian Plain | (Iberia Abyssal Plain, Iberian Abyssal Plain) | North Atlantic Ocean | 43°45′N 13°30′W﻿ / ﻿43.750°N 13.500°W﻿ / 43.750; -13.500 |
| Jamaican Abyssal Plain | | Caribbean Sea (Atlantic Ocean) | |
| Japan Plain | (Japan Abyssal Plain) | Sea of Japan (Pacific Ocean) | 41°30′N 135°0′E﻿ / ﻿41.500°N 135.000°E﻿ / 41.500; 135.000 |
| JOIDES Basin | | Southern Ocean | 74°30′S 174°0′E﻿ / ﻿74.500°S 174.000°E﻿ / -74.500; 174.000 |
| Labrador Basin | (Labrador Sea Basin) | North Atlantic Ocean | 53°0′N 48°0′W﻿ / ﻿53.000°N 48.000°W﻿ / 53.000; -48.000 |
| Laurentian Abyss | | North Atlantic Ocean | |
| Lichte Trough | | Antarctica Ocean | 76°25′S 30°0′W﻿ / ﻿76.417°S 30.000°W﻿ / -76.417; -30.000 |
| Madeira Abyssal Plain | (Madeira Plain) | North Atlantic Ocean | 32°0′N 21°0′W﻿ / ﻿32.000°N 21.000°W﻿ / 32.000; -21.000 |
| Makarov Basin | one of two sub-basins of the Amerasia Basin. | Arctic Ocean | |
| Mascarene Plain | (Madagascar Basin, Malagasy Abyssal Plain, Seychelles-Mauritius Plateau) | Indian Ocean | 19°0′S 52°0′E﻿ / ﻿19.000°S 52.000°E﻿ / -19.000; 52.000 |
| Melanesian Basin | | | |
| Mendeleyev Plain | (Mendeleyev Abyssal Plain) | Arctic Ocean | 81°0′N 170°0′W﻿ / ﻿81.000°N 170.000°W﻿ / 81.000; -170.000 |
| Mid Indian Abyssal Plain | (Mid-Indian Basin) | Indian Ocean | |
| Mornington Abyssal Plain | | South Pacific Ocean | |
| Namibia Abyssal Plain | | South Atlantic Ocean | |
| Nansen Basin | One of two sub-basins of the Eurasian Basin. | Arctic Ocean | |
| Nares Plain | (Fosse Nares, Nares Abyssal Plain, Nares Deep, Nares Tiefe) | North Atlantic Ocean | 23°30′N 63°0′W﻿ / ﻿23.500°N 63.000°W﻿ / 23.500; -63.000 |
| Natal Basin | | | |
| Newfoundland Basin | | North Atlantic Ocean | 43°30′N 45°0′W﻿ / ﻿43.500°N 45.000°W﻿ / 43.500; -45.000 |
| North Australian Basin | (Argo Abyssal Plain, Bassin Nord de l' Australie, Severo-Avstralijskaja Kotlovina) | Indian Ocean | 14°30′S 116°30′E﻿ / ﻿14.500°S 116.500°E﻿ / -14.500; 116.500 |
| North Polar Basin | (consists of the Amerasia Basin and the Eurasian Basin) | | |
| Northwest Pacific Basin | | | |
| Northwind Plain USCGC Northwind (WAGB-282) | (Northwind Abyssal Plain) | Arctic Ocean | 76°0′N 161°0′W﻿ / ﻿76.000°N 161.000°W﻿ / 76.000; -161.000 |
| Okhotsk Abyssal Plain | | Sea of Okhotsk (western Pacific Ocean) | |
| Oman Plain | (Arabian Basin, Oman Abyssal Plain) | Arabian Sea (Indian Ocean) | 23°0′N 61°0′E﻿ / ﻿23.000°N 61.000°E﻿ / 23.000; 61.000 |
| Panama Plain | (Clark Abyssal Plain) | Caribbean Sea (Atlantic Ocean) | 11°0′N 79°0′W﻿ / ﻿11.000°N 79.000°W﻿ / 11.000; -79.000 |
| Papua Plain | (Papua Abyssal Plain) | South Pacific Ocean | 14°0′S 151°30′E﻿ / ﻿14.000°S 151.500°E﻿ / -14.000; 151.500 |
| Para Abyssal Plain | | North Atlantic Ocean | |
| Penrhyn Basin | | | |
| Pernambuco Plain | (Pernambuco Abyssal Plain) | South Atlantic Ocean | 7°30′S 27°0′W﻿ / ﻿7.500°S 27.000°W﻿ / -7.500; -27.000 |
| Perth Plain | (Perth Abyssal Plain, Perth Basin, West Australian Basin) | Indian Ocean | 28°30′S 110°0′E﻿ / ﻿28.500°S 110.000°E﻿ / -28.500; 110.000 |
| Peru Basin | | | |
| Pole Plain | (Central Polar Basin, Pole Abyssal Plain) | Arctic Ocean | 89°0′N 45°0′E﻿ / ﻿89.000°N 45.000°E﻿ / 89.000; 45.000 |
| Porcupine Abyssal Plain | (Porcupine Plain, West European Plain) | North Atlantic Ocean | 49°0′N 16°0′W﻿ / ﻿49.000°N 16.000°W﻿ / 49.000; -16.000 |
| Raukumara Abyssal Plain | | South Pacific Ocean | |
| Rhodes Basin | (Rhodes Abyssal Plain, Ró2dhos Basin) | Sea of Crete (Mediterranean Sea) | 35°55′N 28°30′E﻿ / ﻿35.917°N 28.500°E﻿ / 35.917; 28.500 |
| Roggeveen Basin | | | |
| Sardino-Balearic Plain | (Algerian Plain, Balearic Abyssal Plain, Balearic Plain, Sardino-Balearic Abyssal Plain) | Mediterranean Sea | 39°0′N 6°20′E﻿ / ﻿39.000°N 6.333°E﻿ / 39.000; 6.333 |
| Seine Plain | (Seine Abyssal Plain) | North Atlantic Ocean | 34°0′N 12°15′W﻿ / ﻿34.000°N 12.250°W﻿ / 34.000; -12.250 |
| Siberian Abyssal Plain | | Arctic Ocean | |
| Sicilia Plain | (Messina Abyssal Plain, Sicily Plain) | Mediterranean Sea | 36°0′N 18°0′E﻿ / ﻿36.000°N 18.000°E﻿ / 36.000; 18.000 |
| Sierra Leone Plain | (Sierra Leone Abyssal Plain, Sierra Leone Basin) | North Atlantic Ocean | 5°0′N 17°0′W﻿ / ﻿5.000°N 17.000°W﻿ / 5.000; -17.000 |
| Sigsbee Deep | (Mexico Basin, Sigsbee Abyssal Plain, Sigsbee Deep, Sigsbee Basin) | Gulf of Mexico (Atlantic Ocean) | 23°30′N 93°0′W﻿ / ﻿23.500°N 93.000°W﻿ / 23.500; -93.000 |
| Silver Plain | (Silver Abyssal Plain) | North Atlantic Ocean | 22°30′N 69°30′W﻿ / ﻿22.500°N 69.500°W﻿ / 22.500; -69.500 |
| Sirte Basin | (Ionian Abyssal Plain, Sidra Abyssal Plain, Sidra Plain, Sirte Abyssal Plain, Surt Plain) | Libyan Sea (Mediterranean Sea) | 34°10′N 19°22′E﻿ / ﻿34.167°N 19.367°E﻿ / 34.167; 19.367 |
| Sohm Abyssal Plain | (Fosse de Suhm, Plaine Sohm, Sohm Deep, Sohm Plain, Suhm Abyssal Plain, Suhm Deep, Suhm Plain) | North Atlantic Ocean | 36°0′N 55°0′W﻿ / ﻿36.000°N 55.000°W﻿ / 36.000; -55.000 |
| Somali Plain | (Somali Abyssal Plain, Somali Basin) | Indian Ocean | 1°0′N 51°30′E﻿ / ﻿1.000°N 51.500°E﻿ / 1.000; 51.500 |
| South Australian Plain | (Eyre Abyssal Plain, Great Bight Abyssal Plain, South Australian Abyssal Plain) | Indian Ocean | 37°30′S 130°0′E﻿ / ﻿37.500°S 130.000°E﻿ / -37.500; 130.000 |
| South China Basin | (South China Sea Abyssal Plain) | South China Sea (Pacific Ocean) | 15°0′N 115°0′E﻿ / ﻿15.000°N 115.000°E﻿ / 15.000; 115.000 |
| Southeast Pacific Basin | | | |
| South Fiji Basin | | | |
| South Indian Plain | (South Indian Abyssal Plain, South Indian Basin, South Indian Ocean Plain) | Southern Ocean | 59°0′S 125°0′E﻿ / ﻿59.000°S 125.000°E﻿ / -59.000; 125.000 |
| South West Pacific Abyssal Plain | (South West Pacific Basin) | South Pacific Ocean | |
| Tagus Abyssal Plain | (Tagus Plain) | North Atlantic Ocean | 37°30′N 12°0′W﻿ / ﻿37.500°N 12.000°W﻿ / 37.500; -12.000 |
| Tasman Abyssal Plain | (Tasman Plain, Eastern Australian Abyss, Tasman Basin) | Tasman Sea (South Pacific Ocean) | 34°30′S 153°15′E﻿ / ﻿34.500°S 153.250°E﻿ / -34.500; 153.250 |
| Town Abyssal Plain | | South Atlantic Ocean | |
| Tsushima Basin | (Ulleung Basin) | Korea Strait (Sea of Japan, Pacific Ocean) | 36°35′N 131°48′E﻿ / ﻿36.583°N 131.800°E﻿ / 36.583; 131.800 |
| Tufts Plain | (Tufts Abyssal Plain) | North Pacific Ocean | 47°0′N 140°0′W﻿ / ﻿47.000°N 140.000°W﻿ / 47.000; -140.000 |
| Tyrrhenian Plain | (Tyrrhenian Abyssal Plain) | Tyrrhenian Sea (Mediterranean Sea) | 40°0′N 12°45′E﻿ / ﻿40.000°N 12.750°E﻿ / 40.000; 12.750 |
| Valdivia Abyssal Plain | | Southern Ocean | 62°30′S 70°0′E﻿ / ﻿62.500°S 70.000°E﻿ / -62.500; 70.000 |
| Venezuelan Plain | (Venezuela Abyssal Plain) | Caribbean Sea (Atlantic Ocean) | 14°0′N 67°0′W﻿ / ﻿14.000°N 67.000°W﻿ / 14.000; -67.000 |
| Vidal Abyssal Plain | | North Atlantic Ocean | |
| Weddell Plain | (Weddell Abyssal Plain) | Southern Ocean | 65°0′S 20°0′W﻿ / ﻿65.000°S 20.000°W﻿ / -65.000; -20.000 |
| Wrangellia Terrane | (Wrangel Abyssal Plain) | Arctic Ocean | 81°0′N 160°0′E﻿ / ﻿81.000°N 160.000°E﻿ / 81.000; 160.000 |
| Yamato Basin | | Sea of Japan (Pacific Ocean) | 37°30′N 135°0′E﻿ / ﻿37.500°N 135.000°E﻿ / 37.500; 135.000 |
| Yucatán Abyssal Plain | (Guatemala Basin) | Caribbean Sea (Atlantic Ocean) | |

## Oceanic trenches

Oceanic trenches are long, narrow topographic depressions of the seabed. They are the deepest parts of the ocean floor, and they define one of the most important natural boundaries on the Earth's solid surface: the one between two lithospheric plates. Trenches are a distinctive morphological feature of plate boundaries. Trenches are found in all oceans with the exception of the Arctic Ocean and they are most common in the North and South Pacific Oceans.
There are three types of lithospheric plate boundaries: 1.) divergent (where lithosphere and oceanic crust is created at mid-ocean ridges), 2.) convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and 3.) transform (where two lithospheric plates slide past each other).
An oceanic trench is a type of convergent boundary at which two oceanic lithospheric slabs meet; the older (and therefore denser) of these slabs flexes and subducts beneath the other slab. Oceanic lithosphere moves into trenches at a global rate of about a tenth of a square meter per second. Trenches are generally parallel to a volcanic island arc, and about 200 km from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 10,911 m (35,798 ft) below sea level.

### List of oceanic trenches

The following is a list of the deepest parts of the Earth's oceans and seas (all depths are measured from sea level):
| | Name | Location | Depth (meters) | Depth (feet) | Depth (miles) |
| 1 | Challenger Deep | Izu–Bonin–Mariana Arc, Mariana Trench, Pacific Ocean | 11,034 | 36,197 | 6.86 |
| 2 | Tonga Trench | Pacific Ocean | 10,882 | 35,702 | 6.76 |
| 3 | Emden Deep | Philippine Trench, Pacific Ocean | 10,545 | 34,580 | 6.54 |
| 4 | Kuril–Kamchatka Trench | Pacific Ocean | 10,542 | 34,449 | 6.52 |
| 5 | Kermadec Trench | Pacific Ocean | 10,047 | 32,963 | 6.24 |
| 6 | Izu–Ogasawara Trench | Pacific Ocean | 9,810 | 32,087 | 6.08 |
| 7 | Japan Trench | Pacific Ocean | 9,000 | 29,527 | 5.59 |
| 8 | Puerto Rico Trench | Atlantic Ocean | 8,605 | 28,232 | 5.35 |
| 9 | Yap Trench | Pacific Ocean | 8,527 | 27,976 | 5.30 |
| 10 | Richards Deep | Peru–Chile Trench, Pacific Ocean | 8,065 | 26,456 | 5.01 |
| 11 | Diamantina Deep | Diamantina fracture zone, Indian Ocean | 8,047 | 26,401 | 5.00 |
| 12 | Romanche Trench | Atlantic Ocean | 7,760 | 25,460 | 4.82 |
| 13 | Cayman Trough | Caribbean | 7,687 | 25,238 | 4.78 |
| 14 | Aleutian Trench | Pacific Ocean | 7,679 | 25,194 | 4.77 |
| 15 | Sunda Trench | Indian Ocean | 7,455 | 24,460 | 4.63 |
| 16 | Weber Deep | Banda Sea | 7,351 | 24,117 | 4.56 |
| 17 | South Sandwich Trench | Atlantic Ocean | 7,431 | 24,380 | 4.62 |
| 18 | Dordrecht Deep | Indian Ocean | 7,019 | 23,028 | 4.36 |
| 19 | Middle America Trench | Pacific Ocean | 6,669 | 21,880 | 4.14 |
| 20 | Puysegur Trench | Pacific Ocean | 6,300 | 20,700 | 3.9 |
| 21 | Vityaz Trench | Pacific Ocean | 6,150 | 20,177 | 3.8 |
| 22 | Sulu Trench | South China Sea | 5,600 | 18,400 | 3.48 |
| 23 | Litke Deep | Eurasian Basin, Arctic Ocean | 5,450 | 17,881 | 3.39 |
| 24 | Manila Trench | South China Sea | 5,400 | 17,700 | 3.36 |
| 25 | Calypso Deep | Hellenic Trench, Mediterranean | 5,267 | 17,280 | 3.27 |
| 26 | Ryukyu Trench | Pacific Ocean | 5,212 | 17,100 | 3.24 |
| 27 | Murray Canyon | Southern Ocean, Australia | 5,000 | 16,400 | 3.1 |
^* Entries marked are the deepest parts of their respective water bodies, but are not oceanic trenches.

## Oceanic plateau

An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous provinces. Continental crust has the highest amount of silicon (such rock is called felsic). Oceanic crust has a smaller amount of silicon (mafic rock).
The anomalous volcanism associated with the formation of oceanic plateaux at the time of the Cenomanian–Turonian boundary (90.4 million years) ago may have been responsible for the environmental disturbances that occurred at that time. The physical manifestations of this were elevated atmospheric and oceanic temperatures, a significant sea-level transgression, and a period of widespread anoxia, leading to the extinction of 26% of all genera. These eruptions would also have resulted in the emission of large quantities of carbon dioxide into the atmosphere, leading to global warming. Additionally, the emission of sulfur monoxide, hydrogen sulfide, carbon monoxide, and halogens into the oceans would have made seawater more acidic resulting in the dissolution of carbonate, and further release of CO$_2$. This runaway greenhouse effect was probably put into reverse by the decline of the anomalous volcanic activity and by increased CO$_2$-driven productivity in oceanic surface waters, leading to increased organic carbon burial, black shale deposition, anoxia and mass extinction in the ocean basins.

### List of oceanic plateaus

* Campbell Plateau (South Pacific)
* Challenger Plateau (South Pacific)
* Agulhas Plateau (Southwest Indian)
* Caribbean–Colombian Plateau (Caribbean)
* Exmouth Plateau (Indian)
* Hikurangi Plateau (Southwest Pacific)
* Kerguelen Plateau (Indian)
* Manihiki Plateau (Southwest Pacific)
* Marquesas Plateau (Southwest Pacific)
* Mascarene Plateau (Indian)
* Naturaliste Plateau (Indian)
* Ontong Java Plateau (Southwest Pacific)
* Shatsky Rise (North Pacific)
* Vøring Plateau (North Atlantic)
* Wrangellia Terrane (Northeast Pacific)
* Yermak Plateau (Arctic)

## Mid-ocean ridges

A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges (chains), typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor spreading.

### List of mid-ocean ridges

* Aden Ridge
* American–Antarctic Ridge
* Carlsberg Ridge
* Central Indian Ridge
* Chile Rise
* Cocos Ridge
* East Pacific Rise
* East Scotia Ridge
* Explorer Ridge
* Gakkel Ridge (Mid-Arctic Ridge)
* Gorda Ridge
* Juan de Fuca Ridge
* Knipovich Ridge (between Greenland and Spitsbergen)
* Kolbeinsey Ridge (North of Iceland)
* Mid-Atlantic Ridge
* Mohns Ridge
* Norfolk Ridge
* Pacific–Antarctic Ridge
* Palau–Kyushu Ridge
* Reykjanes Ridge (south of Iceland)
* Southeast Indian Ridge
* Southwest Indian Ridge
* West Mariana Ridge