On World Oceans Day in 2021 (8 June), National Geographic announced that it would start counting a fifth ocean: the Southern Ocean around Antarctica. The water hadn't changed. What changed was a map-maker's decision about where one ocean stops and the next begins. Continents and oceans are like that: the land and sea are real, but the lines between them are agreements, and different countries agree on different things.
The seven-continent model
Most schools in English-speaking countries teach seven continents: Africa, Antarctica, Asia, Australia (often called Oceania), Europe, North America and South America.
Ranked by area, using the approximate figures major encyclopaedias give, they run:
- Asia, the biggest, with roughly 30% of the world's land
- Africa
- North America
- South America
- Antarctica, about 14 million km²
- Europe, about 10 million km²
- Australia/Oceania
Exact figures vary a little between sources, depending on which islands each continent gets, so learn the order rather than the decimals.
Other models: six or five continents
Seven isn't the only answer, and a student who says six isn't wrong, just taught differently.
- America as one continent. Much of Latin America and Spain teach North and South America as a single continent, America.
- Eurasia. Russia and some other countries join Europe and Asia, which share one landmass, into Eurasia.
- Five continents. The Olympic rings stand for five inhabited continents: Africa, America, Asia, Europe and Oceania. Antarctica, with no permanent population, is left out.
The Europe–Asia line shows why the models differ. There's no sea between them, so the usual boundary is a convention: the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus and the Turkish Straits. Russia and Turkey both sit on either side of it.
The five oceans
All the oceans are connected, so dividing them is another agreement. The usual five, ranked by area with figures from the CIA World Factbook (final edition, 2026), are:
| Ocean | Area (approx.) |
|---|---|
| Pacific | about 169 million km² |
| Atlantic | about 85 million km² |
| Indian | about 71 million km² |
| Southern | about 22 million km² |
| Arctic | about 16 million km² |
Other sources give different areas, because some include marginal seas in an ocean and some don't.
The Pacific alone covers more area than all the land on Earth put together, and it holds the deepest known point, Challenger Deep in the Mariana Trench.
Who recognises the Southern Ocean
The Southern Ocean circles Antarctica, out to 60°S in the US definition. The US Board on Geographic Names approved the name in 1999, and NOAA uses it. The International Hydrographic Organization, which publishes the reference limits of oceans and seas, included it in its first editions (1928 and 1937) but dropped it in 1953, so many older maps show four oceans. In 2000 its members agreed limits for it again, but the edition setting them out has never been formally adopted. National Geographic added it in 2021. Some countries, Australia among them, draw its northern edge differently.
Easy ones to mix up
- Australia and Oceania. Australia is the landmass; Oceania is the wider region including New Zealand and the Pacific islands.
- Atlantic and Indian. The Atlantic is second, the Indian third. People often swap them.
- Southern and Arctic. The Arctic is the smallest ocean, not the Southern.
- Antarctica and Europe. Antarctica is bigger. Map projections that stretch it along the bottom edge make it hard to judge.
- Greenland. It sits on the North American side, though it's an autonomous territory of the Kingdom of Denmark.
Frequently asked questions
How many continents are there?
Seven in most English-speaking schools, but six (with America or Eurasia joined) or five (the Olympic model) elsewhere. Each is a convention, not a mistake.
What are the 5 oceans in order of size?
Pacific, Atlantic, Indian, Southern and Arctic, largest to smallest, using areas from the CIA World Factbook (final edition, 2026).
Is the Southern Ocean a real ocean?
The US Board on Geographic Names, NOAA and National Geographic recognise it. The International Hydrographic Organization included it until 1953, and the limits it agreed in 2000 have never been formally adopted.
What is the largest continent?
Asia, with roughly 30% of the world's land.
Try it
Name the seven continents from biggest to smallest, then the five oceans, before you flip a card. Then open a world map: where in the world could you stand with the Atlantic on one side and the Pacific on the other, only a short distance apart?