Difference Between Sea and Lake


Sea vs. Lake

There is a very fine line of difference between a lake and a sea. They both are large water bodies, which is the one common factor between them. This also creates confusion, since the Caspian Sea is not a sea but a lake is often confused as such. A lake is a water body surrounded by land on all sides. They are a small living biological eco-system filled with fresh water. Whereas, a sea is composed of saltwater and is larger in size from a lake, surrounding land on most sides.

Comparison Chart

Seas are water bodies which are not enclosed in all the sides and are one of the most important aquatic structures on earth.Lakes are water bodies which are enclosed in all sides and play a small role in the environmental; aspects of a particular place.
Seas are not inland water bodies and are sources of other water bodies like lagoons which are salty and separated from the source by coral reefs or some other geographical structure.Lakes are inland water bodies which are formed as rivers and are separated from the main source by landforms. They’re also formed when water gets deposited in a narrow low lying area in a sloping land whose height is comparatively less than that of its surrounding area.
Seas contain unfathomable diseases and are the home of thousands of organisms.Lakes possess less depth and are home to a fewer number of organisms mostly fishes.
There are no classifications when it comes to seas; they’re either big or small.Lakes are widely classified into various types depending on various source of water, on the basis of formation.
Seas act as sources to many of the water bodies and usually get their water supply from rivers and rainwater.Lakes are water bodies that mostly get their water from glaciers, rivers, seas, and rain.

What is the Sea?

A sea is a large body of saltwater which is surrounded, by land on all sides. More broadly, “the sea” is an interconnected system of Earth’s salty, oceanic waters, which are derived from all sorts of sources like rain, meteoric water, etc. It is considered as one global ocean or as several oceanic divisions. The sea moderates the Earth’s climate and has important roles in the water cycle, carbon cycle, and nitrogen cycle. It is also concerned with the phenomenon regarding rainfall distribution, as breezes carrying moisture from the sea bring rainfall to the adjacent lands. The modern scientific study of the sea, oceanography arrived broadly after the British Challenger expedition of the 1870s. The sea is conventionally divided into five large oceanic sections. The International Hydrographic Organization’s named four oceans (the Atlantic, Pacific, Indian, and Arctic) of which the second-order sections, such as the Mediterranean, are known as seas.


What is Lake?

A lake is an area filled with water, localized in a basin that is surrounded by land. It is found far away from any river or other outlets that serves to feed or drain the lake. Lakes are water bodies, which lie on land and are not part of the ocean, therefore they are distinct from lagoons. They are also larger and deeper than ponds, though there are no official or scientific definitions of lakes. Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams. The lakes are of two types, one whose water supply is usually provided by rivers and rainfall, and another whose water supply is provided by saline water, which is water from the seas. Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciations. Other lakes are found in endorheic basins or along with the courses of mature rivers.

Key Differences

  1. A lake is primarily a freshwater body while a sea possesses a large amount of salt in it.
  2. A sea serves as a sources of water for smaller water bodies such as lagoons. On the other hand, lakes are formed from the freshwater supplied by rivers.
  3. Lakes do not have a permanent life span. They are formed but will eventually die out. Seas are part of the ocean and hence are constant.
  4. Some lakes are considered as seas because early explorers had made confusion in the nomenclature.
  5. Seas are sub-versions of oceans but lakes are not sub-versions of rivers.


Thus, it can be said that even though there lays a large number of differences when it comes to seas and lakes, both of their presence in the environment is necessary. Otherwise, there would be a scarcity of water and the ecological balance will be lost. Steps should be taken in order to lessen the drainage water of sewage, industrial wastes in water bodies because pollution turns the water of these water bodies into something unusable.

Aimie Carlson

Aimie Carlson is an English language enthusiast who loves writing and has a master degree in English literature. Follow her on Twitter at @AimieCarlson