Difference Between Lake and Sea

Lake vs Sea

The main feature that constitutes the difference between lake and sea is whether a particular water body is connected to an ocean. Water is the lifeline of earth and all living organisms. There are many water bodies on earth such as rivers, streams, lakes, ponds, seas, and oceans. While oceans are the largest water bodies of salt water, seas are subsystems of these oceans that are also salt water bodies. While the rest of the water bodies are well defined and demarcated, there is always confusion between lakes and seas as there are some seas that fit into the definition of lakes, whereas some lakes are in fact seas in themselves. This article attempts to clarify these confusions by highlighting the features of lakes and seas.

What is a Lake?

Lake is fresh water surrounded by land. The water in a lake is still while a river is always flowing. Sometimes the water can be saline depending upon the geology of the surrounding and underlying terrain. Calling seas as water bodies containing salt water does not solve confusion as there are lakes with salt water, and there are seas with fresh water. There are seas that are smaller than some huge lakes of the world. To understand these anomalies, one must keep in mind that lakes are not permanent water bodies. They form, reach maturity and die. The confusion between lake and sea also arises because of the way some of the water bodies were named in earlier times by their explorers. Dead Sea and Caspian Sea are not exactly seas but lakes, but they are known as seas in the world. May be the huge size of Caspian Sea confused people and they preferred to call this lake a sea. It is enclosed by land on all sides, which is a distinguishing characteristic of a lake. Also, it has no connection to an ocean whatsoever which makes it a perfect lake.

Difference Between Lake and Sea

Lake Tahoe

What is a Sea?

Sea is a part of the ocean that is partly surrounded by land, and has salty water. Oceans are bigger and have no identifiable boundaries. There are 4 oceans in the world but 108 seas. Seas are permanent on the geological time scale. On the other hand, some seas get cut off with the feeding ocean and with continuing fresh water getting added from rivers and other sources, salinity goes down, so much so that they contain freshwater in the last. Black Sea in this connection is one example, which has alternated between salt water body and fresh water body over geological time scale.

Lake vs Sea

Baltic Sea

What is the difference between Lake and Sea?

• Lake is an inland water body, while sea is a part of the ocean that is surrounded by land.

• Lake is smaller than sea though, there are some lakes bigger than some of the seas.

• Lakes contain fresh water in general though there are some that contain salty water.

• Sea, being a part of the ocean is a salt water body.

• Lake is not permanent on the geological scale, and get formed, matures, and finally dies.

• Seas are more or less permanent on geological time scale.

• Much of the confusion between a lake and a sea arose because of wrong nomenclature by explorers of earlier times.

• At times, you may have the chance to see the lake bed. However, though the coastline of a sea changes, the bed of a sea is always hidden.

• It is also possible that the confusion between lake and sea came into being because of how different nations identified each water body. In English, a lake or sea is given the name by considering whether or not the water body is landlocked. If it is a sea, it has a connection with the ocean. That means it is not landlocked. If it is a lake, it does not have a connection with the ocean. That means it is landlocked or surrounded by land. For other languages, the salinity of the water may have been the distinguishing factor of a lake or a sea. If it is salty, then it is a sea and it is not salty, then it is a lake. That can explain why Caspian Sea is named a sea when clearly it is a lake.


Images Courtesy:

  1. Lake Tahoe on the border of California and Nevada by Michael (CC BY 2.0)
  2. Baltic Sea by Argonowski (CC BY 3.0)