The oceans of the world: the five oceans and their facts
The Pacific, Atlantic, Indian, Southern and Arctic oceans — the largest, the deepest and the smallest, how the Indian Ocean got its name, and why oceans matter to us.
Rohit Tandon · 21 October 2026 · 4 min read
About 71% of Earth's surface is covered by water, and most of that water lies in the oceans. In truth all the oceans are connected parts of one huge "world ocean", but for convenience it is divided into five. Here are the oceans of the world with their sizes and what makes each special.
The five oceans, by size
| No. | Ocean | Approx. area | What stands out |
|---|---|---|---|
| 1 | Pacific Ocean | 165 million sq km | The largest and deepest; all the continents together are smaller |
| 2 | Atlantic Ocean | 106 million sq km | Shaped like the letter "S" |
| 3 | Indian Ocean | 70 million sq km | The only ocean named after a country |
| 4 | Southern Ocean | 20 million sq km | Surrounds Antarctica; the most recently recognised |
| 5 | Arctic Ocean | 14 million sq km | The smallest and shallowest; mostly covered in ice |
The Pacific: the largest and the deepest
The Pacific Ocean covers about a third of Earth's surface. In 1520 the Portuguese navigator Ferdinand Magellan found it calm and named it "Pacific", meaning "peaceful" — in Hindi too it is called "Prashant" — although the world's fiercest storms also form in it. The Mariana Trench lies in this ocean, and its deepest point, the "Challenger Deep", is about 11 kilometres deep. Around its edges runs a belt of volcanoes and earthquakes called the "Ring of Fire".
The Indian Ocean and India
The Indian Ocean is named after India — the only ocean in the world named after a country. Two large arms of it surround India: the Arabian Sea to the west and the Bay of Bengal to the east, the largest bay in the world. India's sea trade, fisheries, navy and monsoon are all tied to the Indian Ocean. According to a measurement made by a newer method, India's coastline is about 11,098 kilometres long.
Did you know? The longest mountain range in the world is hidden under the sea — the "mid-ocean ridge", which runs about 65,000 kilometres around the whole planet. The part running down the middle of the Atlantic is called the "Mid-Atlantic Ridge", and Iceland sits on top of it.
Why do the oceans matter to us?
- Oxygen: tiny sea plants (phytoplankton) make about half of Earth's oxygen.
- Weather: the oceans store and spread the Sun's heat. India's monsoon, too, depends on moisture rising from the Indian Ocean.
- Food and jobs: the food and livelihoods of hundreds of millions of people come from the sea.
- Trade: most of the world's goods travel between countries by ship along sea routes.
- A climate shield: the oceans absorb a large share of the carbon dioxide released by humans.
Threats to the oceans
Plastic waste, oil spills, overfishing and rising temperatures are big threats to the oceans. In warming water, coral reefs turn white and begin to die, and as carbon dioxide dissolves, sea water is slowly becoming more acidic. "World Oceans Day" is observed every year on 8 June. Read about the sea's most destructive waves in The biggest tsunamis in history.
Key points
- The world has five oceans: the Pacific, Atlantic, Indian, Southern and Arctic.
- The Pacific is the largest and deepest; the Arctic is the smallest and shallowest.
- The deepest point is the Challenger Deep in the Mariana Trench.
- The Indian Ocean is the only ocean named after a country.
- The Bay of Bengal is the largest bay in the world.
Frequently asked questions
Which is the largest ocean in the world?
The Pacific Ocean, which covers about a third of Earth's surface.
Which is the smallest ocean?
The Arctic Ocean.
More articles: Interesting facts about Earth · Geography · Geography questions.
Sources
Found this useful? Share it.