The Earth's surface is divided into two main types of landmasses: continents (land) and oceans (water). About 71% of Earth's surface is covered by water and only 29% is land. This is why Earth is often called the Blue Planet or Watery Planet.
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Key Concepts
Continent: A large, continuous landmass. There are 7 continents: Asia, Africa, North America, South America, Antarctica, Europe, and Australia (Oceania).
Ocean: A vast body of salt water. There are 5 oceans: Pacific, Atlantic, Indian, Arctic, and Southern (Antarctic) Ocean.
Hydrosphere: All the water on Earth — oceans, rivers, lakes, glaciers, and groundwater together form the hydrosphere.
Lithosphere: The solid outer layer of the Earth, including the crust and upper mantle. Continents and ocean floors are parts of the lithosphere.
Continental Shelf: The shallow underwater extension of a continent before the ocean floor drops steeply. Rich in marine life and mineral resources.
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The Seven Continents (Largest to Smallest)
- 1.Asia — Largest continent; home to more than 60% of the world's population.
- 2.Africa — Second largest; the Equator passes through it.
- 3.North America — Third largest; connected to South America.
- 4.South America — Fourth largest; Amazon rainforest is here.
- 5.Antarctica — Fifth; covered entirely in ice; no permanent human settlements.
- 6.Europe — Sixth; separated from Asia by the Ural Mountains.
- 7.Australia — Smallest continent; also a country.
The Five Oceans (Largest to Smallest)
- 1.Pacific Ocean — Largest and deepest ocean; covers more area than all continents combined.
- 2.Atlantic Ocean — Second largest; S-shaped.
- 3.Indian Ocean — Third largest; entirely in the Eastern Hemisphere.
- 4.Southern Ocean — Surrounds Antarctica; recognised as the 5th ocean.
- 5.Arctic Ocean — Smallest and shallowest; mostly frozen.
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Worked Examples
Which is the largest ocean, and how does its area compare to all continents combined?
- The Pacific Ocean is the largest ocean. Its area (about 165 million sq km) is greater than the total land area of all continents combined (about 149 million sq km).
Through which continents does the Equator pass?
- The Equator passes through South America (Brazil), Africa (Kenya, Congo), and Asia (Indonesia/Oceania). It does not pass through North America, Europe, Antarctica, or Australia (mainland).
India is surrounded by which water bodies?
- India is surrounded by the Arabian Sea (west), Bay of Bengal (east), and Indian Ocean (south). All are parts of the Indian Ocean system.
What separates Europe from Asia?
- Europe and Asia are separated by the Ural Mountains, the Ural River, and the Caspian Sea. Together they form the supercontinent called Eurasia.
Name the ocean that lies entirely in the Eastern Hemisphere.
- The Indian Ocean lies entirely in the Eastern Hemisphere (east of 0 degrees longitude).
Which is the only continent that is also a country?
- Australia is both a continent and a country. It is also the smallest continent.
The Mariana Trench is the deepest point on Earth. In which ocean is it located?
- The Mariana Trench is located in the Pacific Ocean, reaching a depth of about 11,000 metres.
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Key Facts Table
- Largest continent: Asia (~44.6 million sq km)
- Smallest continent: Australia (~7.7 million sq km)
- Largest ocean: Pacific (~165 million sq km)
- Deepest point: Mariana Trench, Pacific Ocean (~11,034 m)
- Highest point: Mount Everest, Asia (8,848 m)
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Common mistakes
Common mistakes
Students often forget that the Southern Ocean is recognised as the 5th ocean (it surrounds Antarctica). Also, many students confuse Australia (the continent) with Oceania — Oceania includes Pacific islands too, but Australia is the continental landmass.
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Summary
Earth's surface has 7 continents and 5 oceans. Asia is the largest continent and the Pacific is the largest ocean. About 71% of Earth is water. Oceans and continents are key to understanding world geography, climate, and human settlements.