The five oceans
Seventy per cent of Earth's surface is covered by salt water. That water is divided among five oceans — from the enormous Pacific to the frozen Arctic in the north. They connect the seven continents and drive the climate of the entire planet.
The five oceans in numbers
Area data according to NOAA and the International Hydrographic Organisation (IHO). The Southern Ocean is defined as the waters south of 60°S.
| Ocean | Area (million km²) | Location | Notable feature |
|---|---|---|---|
| Pacific Ocean | 168.7 | Between Asia/Oceania and the Americas | Largest ocean; deepest point (Mariana Trench ~10,935 m) |
| Atlantic Ocean | 85.1 | Between Europe/Africa and the Americas | Mid-Atlantic Ridge; fastest-growing ocean |
| Indian Ocean | 70.6 | South of Asia | Warmest ocean; monsoon circulation |
| Southern Ocean | 21.9 | Around Antarctica (south of 60°S) | Recognised by IHO in 2000; encircles Antarctica |
| Arctic Ocean | 15.6 | Around the North Pole | Smallest and shallowest ocean; largely frozen |
Source: NOAA, IHO — International Hydrographic Organisation.
The Pacific Ocean
The Pacific Ocean — Pacífico in Spanish, named by Fernão de Magalhães in 1520 — is, at 168.7 million km², the largest ocean on Earth. It is bigger than all landmasses combined. From the coast of Asia to the western shores of the Americas it spans almost half the globe.
The world's deepest point lies here: the Mariana Trench, at approximately 10,935 metres below sea level — deeper than Mount Everest is tall. The Ring of Fire encircles the Pacific and accounts for roughly 90% of all earthquakes on Earth.
The Atlantic Ocean
The Atlantic Ocean, at 85.1 million km², connects Europe and Africa to the east with North and South America to the west. It is the busiest ocean for shipping, with historic trade routes that have linked continents for centuries.
Below the surface runs the Mid-Atlantic Ridge: a chain of volcanic peaks stretching the full length of the ocean. In Iceland — one of the few places where this ridge rises above sea level — you can see the two tectonic plates, the North American and the Eurasian, visibly spreading apart by a few centimetres every year.
The Indian Ocean
The Indian Ocean (70.6 million km²) is the warmest ocean. It lies largely in the southern hemisphere, enclosed by Africa to the west, Asia to the north and Australia to the east. The monsoon — the seasonal reversal of winds — originates mainly over the Indian Ocean and delivers the rain that billions of people across South and South-East Asia depend on for agriculture.
The Indian Ocean is also home to some of the largest coral systems on Earth and supports rich fishing grounds that are vital to many coastal states.
The Southern and Arctic Oceans
The Southern Ocean encircles Antarctica completely. At 21.9 million km² it is the youngest formally recognised ocean: the IHO granted it separate status in 2000, National Geographic in 2021. The powerful Antarctic Circumpolar Current — the strongest ocean current on Earth — flows unimpeded around the pole, drawing warm water from the other oceans down into the deep.
The Arctic Ocean (15.6 million km²) is the smallest ocean. It lies largely frozen above the North Pole, largely enclosed by the landmasses of North America, Europe and Asia. Climate change is causing the summer sea ice to melt more each year, opening new shipping routes — such as the Northeast Passage along Siberia — for longer periods.
The oceans and the continents
Oceans and continents are inseparable. The date line runs through the middle of the Pacific; the Indian Ocean monsoon shapes the climate of a third of humanity; the Atlantic Gulf Stream warms Europe. Without the oceans, the continents would look very different — and be far less hospitable.
Together the five oceans hold more than 97% of all water on Earth. They regulate the planet's temperature, produce more than half the oxygen we breathe (via phytoplankton) and absorb a quarter of the CO₂ that humans emit.
Scale comparisonThe Pacific Ocean alone is larger than all seven continents put together. If you dropped every landmass on Earth into the Pacific, there would still be room to spare.
To see how the oceans affect time zones, read the page on the date line.
Frequently asked questions
How many oceans are there?
There are officially five oceans: the Pacific, Atlantic, Indian, Southern and Arctic Oceans. The Southern Ocean was formally recognised by the IHO in 2000.
Which is the largest ocean?
The Pacific Ocean, at 168.7 million km², is the largest. It is bigger than all continents combined (NOAA).
What is the deepest point in the oceans?
The Mariana Trench in the Pacific Ocean is the deepest measured point on Earth: approximately 10,935 metres below sea level (NOAA).
When was the Southern Ocean officially recognised?
The International Hydrographic Organisation (IHO) formally recognised the Southern Ocean in 2000. National Geographic began officially marking it on maps in 2021.
Sources
- NOAA — National Oceanic and Atmospheric Administration (ocean area data)
- IHO — International Hydrographic Organisation, publication S-23 (2000)
- National Geographic — recognition of the Southern Ocean (2021)
- CIA World Factbook — geographical ocean data
- UN World Population Prospects 2024 — population figures for coastal states