Major Seas of the world | Geography for UPSC CSE PDF Download

Geographically, seas are smaller than oceans and are generally found where the land meets the ocean. They are often partially enclosed by landmasses. Seas hold significant geographical, political, and economic importance.

In oceanographic terms, a marginal sea refers to a body of water that is partly enclosed by islands, archipelagos, or peninsulas.

Notable examples of marginal seas include the Arabian Sea, Baltic Sea, Bay of Bengal, Bering Sea, Black Sea, Gulf of California, Gulf of Mexico, Mediterranean Sea, Red Sea, and the four Siberian seas—Barents, Kara, Laptev, and East Siberian Seas.

The key distinctions between marginal seas and the open ocean lie in their depth and closeness to land. Marginal seas are typically shallower and are more directly affected by human activities, river discharge, regional climate, and localized water circulation.

Major (Important) Seas of the world

1. Arabian Sea
2. South China Sea
3. East China Sea
4. Coral Sea
5. Caribbean Sea
6. Mediterranean Sea
7. Ionian Sea
8. Bay of Bengal
9. Arabian Sea
10. Bering Sea
11. Sea of Okhotsk
12. Gulf of Mexico
13. Tasman Sea
14. Hudson Bay
15. Sea of Japan
16. Sea of Azov
17. Caspian Sea
18. Adriatic Sea
19. Baltic Sea
20. Red Sea
21. Yellow Sea
22. Dead Sea
23. Black Sea
24. Tyrrhenian Sea
25. Ligurian Sea
26. Balearic Sea
27. Alboran Sea
28. Sargasso Sea
29. The Aegean Sea

Arabian Sea

• The Arabian Sea is a region of the northern Indian Ocean bounded on the north by Pakistan, Iran, and the Gulf of Oman, on the west by the Gulf of Aden, Guardafui Channel, and the Arabian Peninsula, on the southeast by the Laccadive Sea, on the southwest by the Somali Sea, and on the east by India.

Arabian Sea on World Map

• The Gulf of Aden in the west connects the Arabian Sea to the Red Sea through the strait of Bab-el-Mandeb, and the Gulf of Oman is in the northwest, connecting it to the Persian Gulf.

Arabian Sea on India Map 

Andaman Sea

• The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the northeastern Indian Ocean bounded by the coastlines of Myanmar and Thailand along the Gulf of Martaban and west side of the Malay Peninsula and separated from the Bay of Bengal to its west by the Andaman Islands and the Nicobar Islands.

• Its southernmost end is defined by Breueh Island, an island just north of Sumatra, and communicates with the Malacca Strait.

South China Sea

• Places here are China, Vietnam, Hainan, Malaysia, and the Philippines.
• China is involved in disputes with many countries here. Places in dispute are Paracel, Scarborough Shoal, and The Spratly Islands.

East China Sea

• The East China Sea is a marginal sea of the Western Pacific Ocean, located directly offshore from East China.
• Towards the east of this sea are the Japanese islands of Kyushu and the Ryukyu Islands, towards the south of it is the South China Sea and to the west by the Asian continent.
• The sea connects with the Sea of Japan through the Korea Strait and opens to the north into the Yellow Sea.
• The countries which border the sea include South Korea, Japan, the Republic of China (Taiwan) and the People’s Republic of China.
• In recent times, tensions between China and Japan have risen over the contested Senkaku/Diaoyu islands that lies in this sea, and both nations have raised as incursions into the disputed waters.
• Both countries have increased their military capabilities, particularly their radar and missile systems, in the region.

Adriatic Sea

• The Adriatic Sea is a part of the Mediterranean Sea positioned between the eastern coastline of Italy, and countries of the Balkan Peninsula, from Slovenia, South through Croatia, Montenegro, and to Albania.
• The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan Peninsula.
• The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro, and Slovenia.

Dalmatian coastline

• Dalmatia is one of the four historical regions of Croatia, alongside Croatia proper, Slavonia, and Istria. Dalmatia is a narrow belt of the east shore of the Adriatic Sea, stretching from the island of Rab in the north to the Bay of Kotor in the south.

Black Sea

• The Black Sea is an inland sea located between far southeastern Europe and the far-western edges of the continent of Asia and the country of Turkey.
• It’s bordered by Turkey, and by Bulgaria, Romania, Ukraine, Russia, and Georgia.

The Caspian Sea

• The Caspian Sea is an enclosed body of water between Asia and Europe. It is bordered by Iran, Turkmenistan, Kazakhstan, Azerbaijan, Russia.

Mediterranean Sea

• The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant.

Sargasso Sea

• While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents.
• It is bounded on the west by the Gulf Stream, north, by the North Atlantic Current, east, by the Canary Current, and south, by the North Atlantic Equatorial Current.
• This system of ocean currents forms the North Atlantic Gyre.
• It is the only sea on Earth that has no coastline.

Red Sea

• The Red Sea (Erythraean Sea) is a seawater inlet of the Indian Ocean, lying between Africa and Asia.
• The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden.
• To the north lie the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez (leading to the Suez Canal).
• The sea is underlain by the Red Sea Rift, which is part of the Great Rift Valley.

The six countries bordering the Red Sea are:

• Saudi
• Arabia
• Yemen
• Egypt
• Sudan
• Eritrea
• Djibouti

The Ionian Sea

• The Ionian Sea is an elongated bay of the Mediterranean Sea, south of the Adriatic Sea.
• It is bounded by Southern Italy to the west, southern Albania to the north, and the west coast of Greece.

Marginal Seas of the Arctic Ocean

• Barents Sea
• The Irish Sea

Marginal Seas of the Atlantic Ocean

• Argentine Sea
• Caribbean Sea
• English Channel
• Gulf of Mexico
• Hudson Bay
• Irish Sea
• Labrador Sea
• Mediterranean Sea
• North Sea
• Norwegian Sea
• Scotia Sea

Marginal Seas of the Indian Ocean

• Andaman Sea
• Arabian Sea
• Bay of Bengal
• Java Sea
• Persian Gulf
• Red Sea
• Sea of Zanj

Marginal Seas of the Mediterranean Sea

• Adriatic Sea
• Aegean Sea

Marginal Seas of the Pacific Ocean

• Bering Sea
• Celebes Sea
• Coral Sea
• East China Sea
• Philippine Sea
• Sea of Japan
• Sea of Okhotsk
• South China Sea (another important conflict zone)
• Tasman Sea (between Australia and New Zealand)
• Yellow Sea (by the Korean Peninsula)

Other Seas

• The Caribbean Sea is sometimes defined as a marginal sea, sometimes as a Mediterranean sea.
• The Caspian Sea is also sometimes defined as a marginal sea and also the Dead Sea.