Difference Between Ocean and Sea (With Table)

Both ocean and sea are water bodies that have come to mean the same for most of us. Yet,  they are differentiated by their depth, marine life, and area. Even if we have come to use the terms ‘sea’ and ‘ocean’ as similar meaning words, there is a major difference.

This difference is explained in the manner of their formation of water bodies and the life that they sustain.

Ocean vs Sea

The main difference between ocean and sea is that the ocean is a saltwater body that covers 70% of the world, whereas the sea is a water body of saline water, but it only covers the surface of the earth. Oceans are much bigger and deeper than the sea. Sea eventually merges into an ocean. Sea is where an ocean meets land.

The distance between the shore and the water and its depth decides the marine life in that water body. Another essential difference is that the sea usually has more marine life than the ocean. This is because the sea is smaller and less deep than the ocean, and hence marine life can easily survive.

The oceans are deeper, and they provide for an Inhabitant for most wildlife creatures. Though there is some marine life in the ocean, most thrive and habitat the sea.


Comparison Table Between Ocean and Sea (in Tabular Form)

Parameter of Comparison




Large water body

Comparatively smaller water body



Comparatively less deep


70% of the earth

The surface of the earth

Marine life




Used for industrial purposes like mining for natural gas, oil, etc

Commercialized mainly used for fishing and recreational sport activities


Not enclosed by land

Partially enclosed by land



Saline water


What is Ocean?

The ocean is a large water body between continents. It consists of saltwater. The ocean joins the smaller seas.

The ocean covers 70% of the earth, covering 361,900,000 square kilometers. There are five oceans in the world.

In fact, the ocean is large and deep, which makes it inhabitable for most marine life. The most common marine life that exists in an ocean is the microscopic planktons, the bacteria, and the shrimp.

The main reason for the lack of aquatic plants in the ocean is that as the oceans are deeper, the sunlight doesn’t penetrate it deep enough to allow photosynthesis in plants.

Moreover, the ocean is used for industrial purposes like mining for natural gas, crude oil, etc. diving in the ocean on a submarine is a dangerous feat, but it’s the water body that has crude oil, and natural gas is abundant.

Geographically, the lands are divided by the oceans. The largest ocean is called the Pacific Ocean that covers 1/3rd area of the earth.


What is Sea?

A sea is a water body that is smaller than an ocean. It consists of saline water. The sea is where the ocean meets the land.

There are a total of seven seas in the world. It is partially enclosed by land. An interesting exception is the Caspian Sea, as it is enclosed by land on all sides.

Sea has marine life in abundance as it is nearer to the land and less deep than the ocean, which makes it perfectly habitable for marine life. The temperature and location of a sea define the marine life that will inhabit in that sea.

The beach is less deep, which lets the sunlight penetrate to the surface and allows photosynthesis in plants, which gives us aquatic plants in the sea. Sea has been used for commercial purposes, especially for the finishing industry.

The fishermen travel in the boat and catch fishes. The beach is also used as a tourist spot by allowing cruise, speed boats and jet skis to sail and watch the horizon.

The beaches are used for parties and weddings and are also used for all the water sport.

Sea is used in many ways, even to form electricity by producing hydroelectricity. The sea is a much smaller form of an ocean, but it is more useful than an ocean.

Sea is also used to get salt for commercial purposes. The sea also controls the climates of the earth through the process of evaporation and condensation. All seas are oceans, and ultimately, the smaller seas join to make a large water body called the ocean.

Main Differences Between Ocean and Sea

  1. An ocean is a bigger and deeper water body than the sea.
  2. The ocean isn’t habitable for marine life, whereas the sea has marine life in abundance.
  3. The ocean is used for industrial purposes, whereas the sea is used for commercial purposes.
  4. The ocean covers 70% of the earth, whereas, on the other hand, the sea covers the surface of the area.
  5. The ocean is the joining of the smaller seas, but a sea is where the ocean and land meet.
  6. The ocean doesn’t have land, whereas the sea is enclosed partially by land.
  7. Sunlight cannot penetrate the depth f ocean and reach the surface, but sunlight penetrates the surface of the sea and allows photosynthesis in plants.
  8. Ocean has more deadly marine animals, whereas the sea has a smaller and less dangerous marine life.



Even though we have come to use the ocean and sea as interchangeably in our colloquial use, they have quite some distinctions. Both the water bodies form the majority of our world. They are both useful in their own forms and dangerous in another.

Most seas join to form an ocean, although some seas don’t. An ocean is nothing but an amalgamation of the sea, whereas a sea is where the ocean and land meet.

A sea could be called as a smaller ocean.

The water bodies are different in their depth, area, and marine life habitat. They are used for dividing lands geographically, and what they offer is used for industrialization and commercial business.



  1. https://www.nationalgeographic.org/encyclopedia/sea/
  2. https://www.infoplease.com/world/geography/all-about-oceans