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Oceans / OO

Southern Ocean

Last updated: October 29, 2026

Southern Ocean: CIA World Factbook map from 2021; original boundary notes preserved.
ⓘCIA World Factbook map, February 2021 media edition. Identity reviewed; current boundaries have not been audited. visual contact sheet or original identity check; does not verify current boundaries Boundaries, place names and designations may be dated or disputed; original annotations retained. SHA-256: 3ee97cfe593ed78dc597a7c3a10e071c2269de67de2ea70ca707abd574b5a975. Provenance and inspection record.

Introduction

Background:1

A large body of recent oceanographic research has shown that the Antarctic Circumpolar Current (ACC), an ocean current that flows from west to east around Antarctica, plays a crucial role in global ocean circulation. The region where the cold waters of the ACC meet and mingle with the warmer waters of the north defines a distinct border -- the Antarctic Convergence -- which fluctuates with the seasons but encompasses a discrete body of water and a unique ecologic region. The Convergence concentrates nutrients, which promotes marine plant life, which in turn allows for a greater abundance of animal life. In 2000, the International Hydrographic Organization delimited the waters within the Convergence as a fifth world ocean basin -- the Southern Ocean -- by combining the southern portions of the Atlantic Ocean, Indian Ocean, and Pacific Ocean. The Southern Ocean extends from the coast of Antarctica north to 60 degrees south latitude, which coincides with the Antarctic Treaty region and which approximates the extent of the Antarctic Convergence. As such, the Southern Ocean is now the fourth largest of the world's five ocean basins (after the Pacific Ocean, Atlantic Ocean, and Indian Ocean). It should be noted that inclusion of the Southern Ocean does not imply US Government recognition of this feature as one of the world's primary ocean basins.

Geography

Location:2

body of water between 60 degrees south latitude and Antarctica

Geographic coordinates:3

60 00 S, 90 00 E (nominally), but the Southern Ocean has the unique distinction of being a large circumpolar body of water totally encircling the continent of Antarctica; this ring of water lies between 60 degrees south latitude and the coast of Antarctica and encompasses 360 degrees of longitude

Map references:4

Antarctic Region

Area:5

total:21.96 million sq km
note:includes Amundsen Sea, Bellingshausen Sea, part of the Drake Passage, Ross Sea, a small part of the Scotia Sea, Weddell Sea, and other tributary water bodies

Area - comparative:6

slightly more than twice the size of the US

Coastline:7

17,968 km

Climate:8

sea temperatures vary from about 10 degrees Celsius to -2 degrees Celsius; cyclonic storms travel eastward around the continent and frequently are intense because of the temperature contrast between ice and open ocean; the ocean area from about latitude 40 south to the Antarctic Circle has the strongest average winds found anywhere on Earth; in winter the ocean freezes outward to 65 degrees south latitude in the Pacific sector and 55 degrees south latitude in the Atlantic sector, lowering surface temperatures well below 0 degrees Celsius; at some coastal points intense persistent drainage winds from the interior keep the shoreline ice-free throughout the winter

Ocean volume:9

ocean volume:71.8 million cu km
percent of World Ocean total volume:5.4%

Major ocean currents:10

the cold, clockwise-flowing Antarctic Circumpolar Current (West Wind Drift; 21,000 km long) moves perpetually eastward around the continent and is the world's largest and strongest ocean current, transporting 130 million cubic meters of water per second - 100 times the flow of all the world's rivers; it is also the only current that flows all the way around the planet and connects the Atlantic, Pacific, and Indian Ocean basins; the cold Antarctic Coastal Current (East Wind Drift) is the southernmost current in the world, flowing westward and parallel to the Antarctic coastline

Bathymetry:11

continental shelf:the following are examples of features on the continental shelf of the Southern Ocean (see Figure 2):
continental shelf:Astrid Ridge (see also Figure 4)
continental shelf:Belgrano Bank
continental shelf:Gunnerus Ridge (see also Figure 4)
continental shelf:Hayes Bank
continental shelf:Iselin Bank
continental slope:the following are examples of features on the continental slope of the Southern Ocean (see Figure 2):
continental slope:Amery Basin (Figure 4)
continental slope:Filchner Trough
continental slope:Hillary Canyon
continental slope:Pobeda Canyon (Figure 3)
abyssal plains:the following are examples of features on the abyssal plains of the Southern Ocean (see Figures 2, 3, and 4):
abyssal plains:Amundsen (Abyssal) Plain
abyssal plains:Enderby (Abyssal) Plain
abyssal plains:South Indian/Australian-Antarctic Basin
abyssal plains:Southeast Pacific/Bellinghausen Basin
abyssal plains:Weddell (Abyssal) Plain
mid-ocean ridge:the following are examples of mid-ocean ridges on the floor of the Southern Ocean (see Figure 2):
mid-ocean ridge:Pacific-Antarctic Ridge (Figure 3)
undersea terrain features:the following are examples of undersea terrain features on the floor of the Southern Ocean (see Figure 2):
undersea terrain features:Akopov Seamounts (Figure 3)
undersea terrain features:De Gerlache Seamounts (see also Figure 3, 4)
undersea terrain features:Endurance Ridge (Figure 4)
undersea terrain features:Marie Byrd Seamount (see also Figure 3)
undersea terrain features:Maud Rise (see also Figure 4)
undersea terrain features:Scott Seamounts (see also Figure 3)
ocean trenches:the following are examples of ocean trenches on the floor of the Southern Ocean (see Figure 2):
ocean trenches:South Sandwich Trench (Figure 4; the deepest location in the Southern Ocean)
atolls:none, due to the extremely cold water

Elevation:12

highest point:sea level
lowest point:southern end of the South Sandwich Trench -7,434 m unnamed deep
mean depth:-3,270 m
ocean zones:the ocean is divided into three zones based on depth and light level; sunlight entering the water may travel about 1,000 m into the oceans under the right conditions, but there is rarely any significant light below 200 m
ocean zones:euphotic zone : the upper 200 m (656 ft) is also called "sunlight" zone; only a small amount of light penetrates beyond this depth
ocean zones:dysphotic zone : between 200 m (656 ft) and 1,000 m (3,280 ft), and also called the twilight zone; the intensity of light rapidly dissipates as depth increases, and photosynthesis is no longer possible
ocean zones:aphotic zone : below 1,000 m (3,280 ft) and also called the midnight zone; sunlight does not penetrate to these depths

Natural resources:13

probable large oil and gas fields on the continental margin; manganese nodules, possible placer deposits, sand and gravel, fresh water as icebergs; krill, fish

Natural hazards:14

huge icebergs with drafts up to several hundred meters; smaller bergs and iceberg fragments; sea ice (generally 0.5 to 1 m thick) with sometimes dynamic short-term variations and with large annual and interannual variations; deep continental shelf floored by glacial deposits varying widely over short distances; high winds and large waves much of the year; ship icing, especially May-October; most of region is remote from sources of search and rescue

Geography - note:15

the major chokepoint is the Drake Passage between South America and Antarctica; the Polar Front (Antarctic Convergence) is the best natural definition of the northern extent of the Southern Ocean; it is a distinct region at the middle of the Antarctic Circumpolar Current that separates the cold polar surface waters to the south from the warmer waters to the north; the Front and the Current extend entirely around Antarctica, reaching south of 60 degrees south near New Zealand and near 48 degrees south in the far South Atlantic, coinciding with the path of the maximum westerly winds

Environment

Environmental issues:16

natural and man-made changes to the ocean's physical, chemical, and biological systems

International environmental agreements:17

the Southern Ocean is subject to all international agreements regarding the world's oceans; in addition, it is subject to these agreements specific to the Antarctic region: International Whaling Commission (prohibits commercial whaling south of 40 degrees south [south of 60 degrees south between 50 degrees and 130 degrees west]); Convention on the Conservation of Antarctic Seals (limits sealing); Convention on the Conservation of Antarctic Marine Living Resources (regulates fishing)

note:mineral exploitation except for scientific research is banned by the Environmental Protocol to the Antarctic Treaty; additionally, many nations (including the US) prohibit mineral resource exploration and exploitation south of the fluctuating Polar Front (Antarctic Convergence), which is in the middle of the Antarctic Circumpolar Current and serves as the dividing line between the cold polar surface waters to the south and the warmer waters to the north

Climate:18

sea temperatures vary from about 10 degrees Celsius to -2 degrees Celsius; cyclonic storms travel eastward around the continent and frequently are intense because of the temperature contrast between ice and open ocean; the ocean area from about latitude 40 south to the Antarctic Circle has the strongest average winds found anywhere on Earth; in winter the ocean freezes outward to 65 degrees south latitude in the Pacific sector and 55 degrees south latitude in the Atlantic sector, lowering surface temperatures well below 0 degrees Celsius; at some coastal points intense persistent drainage winds from the interior keep the shoreline ice-free throughout the winter

Marine fisheries:19

the Southern Ocean fishery is relatively small with a total catch of 388,901 mt in 2021; the Food and Agriculture Organization has delineated three regions in the Southern Ocean (Regions 48, 58, 88) that generally encompass the waters south of 40° to 60° South latitude; the most important producers in these regions include Norway (241,408 mt), China (47,605 mt), and South Korea (39,487 mt); Antarctic krill made up 95.5% of the total catch in 2021, while other important species include Patagonian and Antarctic toothfish

Regional fisheries bodies:Commission for the Conservation of Antarctic Marine Living Resources

Government

Country name:20

etymology:the International Hydrographic Organization (IHO) has not formally adopted the definition of the Southern Ocean as the waters south of 60 degrees south; the definition, however, was circulated in a draft edition of the IHO's Names and Limits of Oceans and Seas in 2002 and has since become the de facto name for many nations and organizations, including the CIA

Transportation

Transportation - note:21

Drake Passage offers alternative to transit through the Panama Canal

Historical observations

Notes & sources

  1. Background. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  2. Location. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  3. Geographic coordinates. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  4. Map references. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  5. Area. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  6. Area - comparative. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  7. Coastline. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  8. Climate. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  9. Ocean volume. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  10. Major ocean currents. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  11. Bathymetry. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  12. Elevation. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  13. Natural resources. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  14. Natural hazards. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  15. Geography - note. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  16. Environmental issues. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  17. International environmental agreements. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  18. Climate. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  19. Marine fisheries. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  20. Country name. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
  21. Transportation - note. Reference edition; observation: dates as stated in text. Field last updated: not supplied; profile fallback: 2025-08-28 05:45:50 -0400 (not a field revision date); needs review. Reference source. Edition last checked 2026-10-29 (retrieval only). ↩
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