Ocean vs Sea – Difference and Comparison

What is Ocean?

In general, when people say the sea, they mean the same thing as the ocean. That is, a vast, continuous body of saline water that covers most of the globe. More specifically, the sea is “a division of these sea areas of considerable extent, more or less clearly delimited by land boundaries”.

More than 70% of the earth’s surface is covered by the ocean. Some of the major notable seas that fit this definition include the Mediterranean Sea, the Caribbean Sea, the Arabian Sea, the South China Sea and the Red Sea.

The world’s oceans provide at least half of the world’s oxygen and store about 50 times more carbon than the atmosphere. The ocean also influences the Earth’s climate by constantly transporting heat from the equator to the poles.

Most of the water on Earth is stored in oceans, seas and bays, which make up 96.5% of the 1.36 billion of water. About 71% of the earth’s surface is covered by oceans.

What is Sea?

Seas are defined as parts of the ocean partially surrounded by land. Given this definition, there are about 50 seas around the world. However, this number includes bodies of water that are not necessarily considered oceans.

Geographically, seas are smaller than oceans and are located where land and ocean meet. Seas are located at the edges of the ocean and the sea is partially enclosed by the land. Here you can see that the sea is part of the Pacific Ocean.

The stretches of salt water that cover most of the Earth’s surface and surround its land masses are called seas. The sea is a part of the ocean that is partially surrounded by land. However, sometimes the sea is completely surrounded by land, such as the Caspian Sea.

Difference Between Ocean And Sea

The difference between the oceans and the seas is their size. The ocean is a large body of salt water relative to the size of the sea. Furthermore,  the sea can exist as part of the open ocean, or it can be inland and completely separated from the ocean. But both are essential to the existence of plants and animals on Earth.

Technically, “sea” is the term used for small bodies of water, while the term “ocean” is used for large bodies of water.

The sea provides humans with a substantial amount of food, mainly fish. Maritime uses include trade, travel, power generation, warfare, and various recreational activities.

Oceans are bodies of water that make up most of the planet’s hydrosphere. The ocean contains most of the water on Earth.

Comparison Between Ocean and Sea

The ocean covers about 70% of the earth’s surface.The sea consists of salt water, but it is small compared to the ocean.
The largest ocean is the Pacific Ocean, which covers an area of ​​about 60 million square miles. The Arctic Ocean is the smallest ocean of all.The sea is made of salt water. The largest sea is the Mediterranean Sea.  
The ocean is not always close to the land.The sea is near the land.
Marine life in the ocean is usually limited to bacteria, shrimp and microscopic plankton.There are many marine organisms in the sea because sunlight penetrates deep into the sea and enables photosynthesis.
The sea is farther from the land and deeper than the sea, so there is less aquatic life. Because the sea is close to land, the sea is teeming with aquatic life.  


  1. https://www.sciencedirect.com/science/article/pii/S0277379103003494
  2. https://www.science.org/doi/abs/10.1126/science.1085534