Top 10 Largest Oceans and Seas
| Rank | Ocean/Sea | Approximate Area (sq km) | Approximate Area (sq mi) |
|---|---|---|---|
| 1 | Pacific Ocean | 165,250,000 | 63,800,000 |
| 2 | Atlantic Ocean | 106,460,000 | 41,100,000 |
| 3 | Indian Ocean | 70,560,000 | 27,240,000 |
| 4 | Southern Ocean | 20,327,000 | 7,849,000 |
| 5 | Arctic Ocean | 14,060,000 | 5,430,000 |
| 6 | Coral Sea | 4,791,000 | 1,850,000 |
| 7 | Arabian Sea | 3,862,000 | 1,491,000 |
| 8 | South China Sea | 3,685,000 | 1,423,000 |
| 9 | Caribbean Sea | 2,754,000 | 1,063,000 |
| 10 | Mediterranean Sea | 2,510,000 | 970,000 |
Please note that there is some debate about the exact boundaries of the Southern Ocean, so its area may vary depending on the source.
Top 10 Countries with the Largest Areas of Coral Reef
The top 10 countries with the largest areas of coral reef are:
| Country | Reef area (sq km) | Reef area (sq mi) | % of world total |
|---|---|---|---|
| Australia | 344,400 | 133,000 | 30.1 |
| Indonesia | 284,300 | 109,600 | 24.8 |
| Philippines | 260,000 | 100,400 | 22.7 |
| Brazil | 105,000 | 40,500 | 9.2 |
| Papua New Guinea | 78,000 | 30,100 | 6.8 |
| Mexico | 66,000 | 25,600 | 5.7 |
| Cuba | 51,000 | 19,700 | 4.4 |
| Fiji | 13,000 | 5,000 | 1.1 |
| Solomon Islands | 11,000 | 4,300 | 0.9 |
| New Caledonia | 9,000 | 3,500 | 0.8 |
These countries together account for over 90% of the world's coral reefs. Coral reefs are important ecosystems that provide a home to a wide variety of marine life, protect coastlines from erosion, and contribute to the tourism industry.
Top 10 Smallest Seas
| Rank | Sea | Ocean | Approximate area (sq km) | Approximate area (sq mi) |
|---|---|---|---|---|
| 1 | Marmara Sea | Mediterranean Sea | 11,472 | 4,429 |
| 2 | Salish Sea | Pacific Ocean | 17,000 | 6,563 |
| 3 | Balearic Sea | Mediterranean Sea | 85,159 | 32,880 |
| 4 | Andaman Sea | Indian Ocean | 797,700 | 307,995 |
| 5 | Laccadive Sea | Indian Ocean | 786,000 | 303,477 |
| 6 | Yellow Sea | Pacific Ocean | 380,000 | 146,719 |
| 7 | Gulf of Aden | Indian Ocean | 410,000 | 158,302 |
| 8 | Black Sea | Atlantic Ocean | 436,000 | 168,340 |
| 9 | Red Sea | Indian Ocean | 438,000 | 169,463 |
| 10 | Gulf of Mexico | Atlantic Ocean | 1,550,000 | 598,460 |
Note: There is no universally accepted definition of a sea, so this list is based on the International Hydrographic Organization's (IHO) definitions of seas and oceans. The IHO defines a sea as a "relatively enclosed, extensive body of salt water that is connected to an ocean or larger sea in one or more places."
Also note: The Gulf of Mexico is often considered to be a marginal sea of the Atlantic Ocean, but it is also included in this list because it is relatively small compared to other seas and oceans.
Top 10 Smallest Seas with their Oceans
| Rank | Sea | Ocean | Approximate area (sq km) | Approximate area (sq mi) |
|---|---|---|---|---|
| 1 | Marmara Sea | Mediterranean Sea | 11,350 | 4,380 |
| 2 | Andaman Sea | Indian Ocean | 797,700 | 307,900 |
| 3 | Baltic Sea | Atlantic Ocean | 377,000 | 146,000 |
| 4 | Caspian Sea | Enclosed | 371,000 | 143,000 |
| 5 | Libyan Sea | Mediterranean Sea | 350,000 | 140,000 |
| 6 | Mawson Sea | Southern Ocean | 333,000 | 129,000 |
| 7 | Levantine Sea | Mediterranean Sea | 320,000 | 120,000 |
| 8 | Java Sea | Pacific Ocean | 320,000 | 120,000 |
| 9 | Gulf of Thailand | Pacific Ocean | 320,000 | 120,000 |
| 10 | Celtic Sea | Atlantic Ocean | 300,000 | 120,000 |
Note that some seas, such as the Caspian Sea, are considered to be enclosed basins, rather than part of an ocean.
Top 10 Countries with Longest Coastlines
The top 10 countries with the longest coastlines are:
| Rank | Country | Coastline length (km) | Coastline length (mi) |
|---|---|---|---|
| 1 | Canada | 202,080 | 125,567 |
| 2 | Norway | 83,281 | 51,748 |
| 3 | Indonesia | 54,716 | 33,999 |
| 4 | Russia | 37,653 | 23,396 |
| 5 | Philippines | 36,289 | 22,549 |
| 6 | Japan | 29,751 | 18,486 |
| 7 | Australia | 25,760 | 16,007 |
| 8 | United States | 19,924 | 12,380 |
| 9 | Greenland | 44,087 | 27,394 |
| 10 | Brazil | 7,367 | 4,577 |
Please note that the length of a coastline can be difficult to measure accurately, as it depends on how precisely it is measured and how small islands and inlets are counted. The figures in the table above are based on the World Factbook data, which are considered to be the most reliable available.
Top 10 deepest deep sea trenches
The top 10 deepest deep sea trenches, with their deepest points in meters and feet, are as follows:
| Rank | Trench | Deepest point (meters) | Deepest point (feet) |
|---|---|---|---|
| 1 | Mariana Trench | 10,984 ± 25 | 36,037 ± 82 |
| 2 | Tonga Trench | 10,820 | 35,500 |
| 3 | Philippine Trench | 10,540 | 34,580 |
| 4 | Kuril–Kamchatka Trench | 10,542 | 34,587 |
| 5 | Kermadec Trench | 10,047 | 32,963 |
| 6 | Izu-Ogasawara Trench | 9,780 | 32,090 |
| 7 | Japan Trench | 9,009 | 29,557 |
| 8 | Aleutian Trench | 8,556 | 28,070 |
| 9 | Puerto Rico Trench | 8,376 | 27,480 |
| 10 | South Sandwich Trench | 8,264 | 27,113 |
Please note that the depths of these trenches are constantly being refined, as scientists develop new and more accurate measurement method.