14 Difference Between Sea And Ocean (With Similarities)

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Water bodies are an essential element of the Earth’s surface. These water bodies exist in various shapes, sizes and locations with varied characteristics. These water bodies are generally important in various ways. For example sea and Oceans are used for heavy transportation and travelling etc. The Sea and Ocean moderates Earth’s climate and have important roles in the water cycle, carbon cycle and nitrogen cycle. Sea and Oceans also provide substantial supplies of food for humans, mainly fish and mammals. Though the words sea and ocean are commonly used interchangeably in many conversations, the two are generally different in terms of depth, area and marine life.

What Is An Ocean?

An Ocean is a continuous large body of salt water that covers over 70% of the Earth’s surface. In other words, oceans are waters between the continents such as Atlantic Ocean separating Africa and Europe from North/South America; Indian Ocean separating India from Africa, Pacific Ocean separating North and South America from Asia. Generally, Ocean floor is made up of dense basaltic rocks.

According to the international Hydrological Organization, there are generally five major oceans on earth; they include Pacific, Atlantic, Indian, Southern and Arctic oceans. Various water movements distinguish the southern Ocean or the Antarctic Ocean from the Atlantic, Pacific and Indian Ocean.

Below Are major Oceans, in size order, from largest to smallest:

OceanArea
The Pacific Ocean60,060,700 square miles
The Atlantic Ocean29,637,900 square miles
The Indian Ocean26,469,900 square miles
The Southern Ocean7,848,300 square miles
The Arctic Ocean5,427,000 square miles

What You Need To Know About Ocean

  • The ocean is a large body of salt water that covers over 70% of the Earth’s surface.
  • Oceans are found around all the continents.
  • Ocean floor is made up of dense basaltic rock.
  • According to the international Hydrological Organization, there are generally five major oceans on earth; they include Pacific, Atlantic, Indian, Southern and Arctic oceans. Various water movements distinguish the southern Ocean or the Antarctic Ocean from the Atlantic, Pacific and Indian Ocean.
  • Oceans are larger in size by far when compared to seas.
  • All oceans are interconnected with one another. They are bounded by continents or the equator and other imaginary lines.
  • Pacific Ocean is the largest ocean in the world, covering about 60,060,700 square miles.
  • Oceans are deeper than seas. For example the Pacific Ocean has a maximum depth of about 35839 feet.
  • The oceans have a less variety of Marine life forms than Seas.
  • The smallest Ocean of the earth is Arctic Ocean, whereas the Atlantic Ocean is relatively because large parts of its seafloor are made up of continental shelves-parts of the Continents that extend far out into the Ocean.
  • At different parts of the world, the temperatures of the Oceans are different. For example, waters near the poles are very cold due to icebergs while waters around the equator are pretty warm.
  • Marine life in the ocean is quite different from those found in the Seas. It is generally made up of creatures which need less sunlight like phytoplanktons, whales and other creatures.
  • Oceans are generally used for traveling, transportation and industrial uses like natural gas or oil mining.
  • Oceans have currents (ocean currents) which help in balancing the temperature of earth surface.

What Is A Sea?

The sea is a small body of water or small extension part of an ocean and is typically partially contained or enclosed by an area of land. The sea water is also salty water and it is connected to the ocean. The word sea is also used to describe smaller, partly landlocked sections of the ocean and certain large, entirely landlocked, saltwater lakes such as the Caspian Sea, the North Sea, the Red Sea and the Dead Sea. Generally, seas are very close to land or human habitation and the sea floor is made up of granite rock of the continent. There are generally 50 seas around the world, however, Major seas are –Mediterranean Sea, South China Sea, Caribbean Sea, Baltic Sea, Berring, Black, Coral, North and Red Seas.

Marine life in the Seas are somehow different from those in the Oceans, in Oceans there are microscopic organisms, planktons, bacteria, shrimps, big mammals-whale, sharks, dolphin etc. In the Sea, there are both aquatic and amphibian animals that live in the water and on land. This is because they’re shallower and allow more sunlight to penetrate, a factor that promotes photosynthesis, which allows the plants and animals to thrive.

In the examples below, these large seas do happen to be connected to oceans. While this seas of the world list isn’t all-encompassing, it does include the world’s 10 largest seas, in order from largest to smallest:

SeaAreaConnected Ocean
The Mediterranean Sea1,144,800 square milesAtlantic Ocean
The Caribbean Sea1,049,500 square milesAtlantic Ocean
The South China Sea895,400 square milesPacific Ocean
The Bering Sea884,900 square milesPacific Ocean
The Gulf of Mexico615,000 square milesAtlantic Ocean
The Sea of Okhotsk613,800 square milesPacific Ocean
The East China Sea482,300 square milesPacific Ocean
Hudson Bay475,800 square milesArctic Ocean
The Sea of Japan389,100 square milesPacific Ocean
Andaman Sea308,000 square milesIndian Ocean

What You Need To Know About Sea

  • Sea is a large body of salt water that is surrounded by land on all or most sides or that is part of one of the Oceans.
  • The word sea is also used to describe smaller, partly landlocked sections of the ocean and certain large, entirely landlocked, saltwater lakes such as the Caspian Sea, the North Sea, the Red Sea and the Dead Sea.
  • The Sea floor is generally made up of sand or light granite rock of the continent.
  • Major seas are –Mediterranean Sea, South China Sea, Caribbean Sea, Baltic Sea, Berring, Black, Coral, North and Red Seas.
  • All seas are found on the margins of the ocean or areas where the ocean and land meet.
  • Seas are generally a narrow body of water; smaller in size to oceans.
  • Sea is partially surrounded by land as it connects the ocean with the land.
  • Mediterranean Sea also referred to as Great Sea is the largest sea, covering about 1,144,800 square miles. It connects many countries in Africa, Europe and Asia.
  • The sea is not as deep as Ocean. For example, the Caribbean Sea is the deepest sea and has a maximum depth of 22,788 feet deep.
  • Smaller seas are separated from the Oceans by Island chains or underwater ridges, which are referred to as ‘bordering seas’.
  • Seas support a greater variety of marine life than Oceans. This is because they’re shallower and allow more sunlight to penetrate. A factor that promotes photosynthesis, which allows the plants and animals to thrive.
  • The sea is a major source of food supplies for humans, majorly fish, shellfish, mammals and seaweed.
  • Marine life in the sea consists of creatures that are more dependent on sunlight; they are also creatures that can live in both land and water like lobsters, crabs, shrimp, bacteria etc.
  • Seas have various commercial uses like fishing, transportation, recreational and sporting activities.
  • Seas are associated with heavy waves that are not visible in oceans.
  • The Sea moderates Earth’s climate and has important roles in the water cycle, carbon cycle and nitrogen cycle.

Difference Between Sea And Ocean In Tabular Form

BASIS OF COMPARISON OCEAN SEA
Description The ocean is a large body of salt water that covers over 70% of the Earth’s surface.   Sea is a large body of salt water that is surrounded by land on all or most sides or that is part of one of the Oceans.  
Floor Ocean floor is made up of dense basaltic rock.   The Sea floor is generally made up of sand or light granite rock of the continent.  
Major Oceans And Seas There are generally five major oceans on earth; they include Pacific, Atlantic, Indian, Southern and Arctic oceans. Major seas are –Mediterranean Sea, South China Sea, Caribbean Sea, Baltic Sea, Berring, Black, Coral, North and Red Seas.  
Depth Oceans are deeper than seas. For example the Pacific Ocean has a maximum depth of about 35839 feet.   The sea is not as deep as Ocean. For example, the Caribbean Sea is the deepest sea and has a maximum depth of 22,788 feet deep.  
Position All oceans are interconnected with one another. They are bounded by continents or the equator and other imaginary lines.   All seas are found on the margins of the ocean or areas where the ocean and land meet.  
Size Oceans are larger in size by far when compared to seas.   Seas are generally a narrow body of water; smaller in size to oceans.  
Largest Sea & Ocean Pacific Ocean is the largest ocean in the world, covering about 60,060,700 square miles.   Mediterranean Sea also referred to as Great Sea is the largest sea, covering about 1,144,800 square miles.
Connection All oceans are interconnected with one another. They are bounded by continents or the equator and other imaginary lines.   Sea is partially surrounded by land as it connects the ocean with the land.  
Marine Life Variety The oceans have a less variety of Marine life forms than Seas.   Seas support a greater variety of marine life than Oceans.
Currents Oceans have currents (ocean currents) which help in balancing the temperature of earth surface.   Seas are associated with heavy waves that are not visible in oceans.  
Use Oceans are generally used for traveling, transportation and industrial uses like natural gas or oil mining.   Seas have various commercial uses like fishing, transportation, recreational and sporting activities.  
Marine Life Forms Marine life in the ocean is quite different from those found in the Seas. It is generally made up of creatures which need less sunlight. Marine life in the sea consists of creatures that are more dependent on sunlight.

Similarities Between Ocean And Sea

  1. They are both made up of saltwater.
  2. Both support marine life forms.
  3. They are characterized by currents.
  4. They both moderate Earth’s climate and have important roles in the water cycle, carbon cycle and nitrogen cycle.