The world’s largest bodies of water include oceans, seas, gulfs, bays, and lakes. While there is not agreement on the precise size, because the boundaries of bodies of water are not clear, the following charts include some of the biggest. Also of note are the changes in size due to natural and unnatural causes. Lake Chad is worth mentioning in this regard. With an area of over 9,653 sq. mi (25,000 sq. km) in the 1960s — about the size of Lake Erie — Lake Chad was the fourth largest lake in Africa. By the late 1990s, this lake had an area of only 521 sq. mi (1350 sq. km), about 1/3 the size of the Great Salt Lake in Utah.
The first chart is restricted to bodies of salt water. It includes the Southern Ocean, which was recognized in 2000 by the International Hydrographic Organization as a fifth world ocean, joining the Pacific, Atlantic, Indian, and Arctic Oceans. As the chart shows, it is the fourth largest of these five oceans.
| Order | Name | Area in sq mi (sq km) |
| 1. | Pacific Ocean | 60,060,893 (155,557,000) |
| 2. | Atlantic Ocean | 29,637,974 (76,762,000) |
| 3. | Indian Ocean | 26,469,620 (68,556,000) |
| 4. | Southern Ocean | 7,848,299 (20,327,000) |
| 5. | Arctic Ocean | 5,427,052 (14,056,000) |
| 6. | South China Sea | 1,148,500 (2,974,600) |
| 7. | Caribbean Sea | 971,394 (2,515,900) |
| 8. | Mediterranean Sea | 969,116 (2,510,000) |
| 9. | Bering Sea | 872,977 (2,261,000) |
| 10. | Gulf of Mexico | 582,088 (1,507,600) |
| 11. | Sea of Okhotsk | 537,493 (1,392,100) |
| 12. | Sea of Japan/East Sea | 391,083 (1,012,900) |
| 13. | Hudson Bay | 281,893 (730,100) |
| 14. | East China Sea | 256,372 (664,000) |
| 15. | Andaman Sea | 218,109 (564,900) |
| 16. | Black Sea | 196,101 (507,900) |
| 17. | Red Sea | 174,904 (453,000) |
| 18. | Caspian Sea | 143,000 (371,000) |
| 19. | Baltic Sea | 76,762 (415,000) |
Lake Superior, one of the Great Lakes, is the biggest freshwater lake. The other Great Lakes are also among the largest freshwater lakes in the world. The Caspian Sea, while technically a lake, contains saltwater. It is interesting to note that most of these lakes are in the Northern Hemisphere, and the majority are in North America.
| Order | Name and location | Area in sq mi (sq km) |
| 1. | Lake Superior, US/Canada | 31,820 (82,413) |
| 2. | Lake Victoria, Uganda/Tanzania/Kenya | 26,828 (69,484) |
| 3. | Lake Huron, US/Canada | 23,010 (59,596) |
| 4. | Lake Michigan, US | 22,400 (58,016) |
| 5. | Lake Tanganyika, Tanzania | 12,355 (31,999) |
| 6. | Lake Baikal, Russia | 12,162 (31,499) |
| 7. | Great Bear Lake, Canada | 12,000 (31,080) |
| 8. | Great Slave Lake, Canada | 11,170 (28,930) |
| 9. | Lake Nyasa, Tanzania/Mozambique/Malawi | 10,900 (28,231) |
| 10. | Lake Erie, US/Canada | 9,940 (25,744) |
| 11. | Winnipeg Lake, Canada | 9,094 (23,553) |
| 12. | Lake Ontario, US/Canada | 7,540 (19,529) |
