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Distribution of the Ocean – UPSC Geography Notes
Overview: More than 70% of the Earth’s surface is covered by oceans. These vast water bodies are not evenly distributed across the globe but divided into distinct basins separated by continents. Understanding the distribution of oceans helps in studying global climate, ocean currents, and marine biodiversity — key areas for UPSC Geography.
Table of Contents
- 1. Introduction
- 2. Distribution of Land and Water on Earth
- 3. Major Oceans of the World
- 4. Characteristics of Each Ocean
- 5. Comparative Table of Major Oceans
- 6. Importance of Oceanic Distribution
- 7. UPSC Quick Revision Notes
- 8. Previous Year Question
1. Introduction
The surface of the Earth is divided into land and water hemispheres. Water covers about 71% of the Earth's surface, while land occupies the remaining 29%. This uneven distribution of land and water shapes our climate, winds, and life systems.
- Total surface area of Earth: 510 million sq. km
- Water area: 361 million sq. km (71%)
- Land area: 149 million sq. km (29%)
2. Distribution of Land and Water on Earth
The distribution of oceans and continents is not uniform between the hemispheres:
- Land Hemisphere: The hemisphere centered on Europe, Asia, and North America contains most of the land area.
- Water Hemisphere: The opposite hemisphere, centered near New Zealand in the South Pacific Ocean, contains most of the ocean water.
Key Observation: The Northern Hemisphere is called the land hemisphere (≈ 61% land), while the Southern Hemisphere is the water hemisphere (≈ 81% water).
3. Major Oceans of the World
There are five major oceans, arranged from largest to smallest:
- Pacific Ocean
- Atlantic Ocean
- Indian Ocean
- Southern (Antarctic) Ocean
- Arctic Ocean
4. Characteristics of Each Ocean
(1) Pacific Ocean
- Largest and deepest ocean; covers about 46% of total ocean area.
- Bounded by Asia and Australia on the west, and North and South America on the east.
- Contains the world’s deepest point – Mariana Trench (11,034 m).
- Has numerous volcanic islands (Philippines, Japan, Fiji) and is surrounded by the Ring of Fire.
(2) Atlantic Ocean
- Second largest ocean; roughly S-shaped between the Americas and Europe-Africa.
- Covers about 23% of the total ocean area.
- Contains the Mid-Atlantic Ridge — a major underwater mountain range.
- Known for its narrow continental shelf and historical importance in trade and colonization.
(3) Indian Ocean
- Third largest ocean, covering about 20% of the total ocean area.
- Bounded by Africa on the west, Asia on the north, Australia on the east, and the Southern Ocean on the south.
- Has the warmest surface water among all oceans.
- Contains important features like the Mid-Indian Ridge and Chagos Trench.
- Unique because it is bounded on the north by land — the only ocean to do so.
(4) Southern (Antarctic) Ocean
- Encircles Antarctica, extending from 60° S latitude to the continent.
- Fourth largest ocean; connects the Pacific, Atlantic, and Indian Oceans.
- Characterized by cold temperatures, strong westerly winds, and the Antarctic Circumpolar Current.
- Rich in krill and marine biodiversity but largely uninhabited.
(5) Arctic Ocean
- Smallest and shallowest ocean, located around the North Pole.
- Covers about 4% of the total ocean area.
- Surrounded by Eurasia and North America.
- Partly frozen throughout the year; influenced by cold currents and polar ice caps.
5. Comparative Table of Major Oceans
| Ocean | Area (Million sq. km) | Average Depth (m) | Deepest Point |
|---|---|---|---|
| Pacific Ocean | 165 | 4,280 | Mariana Trench (11,034 m) |
| Atlantic Ocean | 106 | 3,930 | Puerto Rico Trench (8,605 m) |
| Indian Ocean | 73 | 3,890 | Java Trench (7,725 m) |
| Southern Ocean | 20 | 4,500 | South Sandwich Trench (7,235 m) |
| Arctic Ocean | 14 | 1,200 | Eurasian Basin (5,450 m) |
6. Importance of Oceanic Distribution
- Regulates global temperature and climate through ocean currents.
- Acts as a major source of oxygen and carbon dioxide exchange.
- Provides food, minerals, and energy resources.
- Influences trade routes, monsoon systems, and human settlement.
- Supports rich marine biodiversity and ecosystems.
7. UPSC Quick Revision Notes
Major oceans → Pacific, Atlantic, Indian, Southern, Arctic.
Pacific → largest & deepest; Mariana Trench.
Atlantic → 2nd largest; Mid-Atlantic Ridge.
Indian → warmest; bounded by land to north.
Southern → surrounds Antarctica; cold & windy.
Arctic → smallest & shallowest; partly frozen.
Land hemisphere → North; Water hemisphere → South.
8. Previous Year Question
Q. Which of the following oceans has the largest area?
(a) Indian Ocean
(b) Atlantic Ocean
(c) Pacific Ocean
(d) Arctic Ocean
Answer: (c) Pacific Ocean
Related Keywords
Distribution of Oceans UPSC Notes, Oceanography UPSC, Major Oceans of the World, Pacific and Atlantic Oceans, Geography Notes for UPSC, Physical Geography.
Sources: NCERT Class XI – Fundamentals of Physical Geography, Goh Cheng Leong (Certificate Physical and Human Geography), National Geographic Ocean Database (simplified for UPSC aspirants).
