difference between lagoon and lake

Is there any difference between lagoon and lake? Are they both not isolated stretches of water?  

Although they both look identical, these two bodies of water are actually quite different

And you can notice the difference between where these two resources are located and how they are accessed.

And that is why it is going to be an interesting comparison of lake vs lagoon, which will make your next outdoor experience more enjoyable too.

Lagoons and lakes may look similar but have different formations, geological features, size, water chemistry, ecosystem and biodiversity.  

What is the Difference between Lagoon and Lake?

distinguishing lagoons from lakes

A South African study distinguished between marine-supporting lagoons and non-supporting lakes.

If marine life can thrive there, it is clearly a lagoon and not isolated from the ocean. It is a lake if only freshwater organisms can be found there.

While lakes account for less than 1% of Earth’s total area, lagoons take up 12% of its coastlines.

How else are lakes and lagoons comparable and dissimilar?

Well, here is a bit about the difference between lake and lagoon:

  • Formation and Geological Features
  • Size, Depth and Water Chemistry
  • Ecosystem and Biodiversity

Formation and Geological Features

formation and geological features

Both lakes and lagoons are different in terms of their formation and geological features.

These features are used to describe the processes and qualities that shape these distinct types of water bodies, as well as the corresponding geological structures and ecosystems

Formation and Geological Features of Lakes

The land surrounds lakes on all sides, making them an inland body of water.

Many natural processes can give rise to lakes, such as:

  • Glacial movement
  • Volcanic eruption
  • Tectonic upheaval
  • Erosion 
Glacial Lakes

Glacial lakes are generated when melting ice or precipitation fills depressions left behind after glaciers recede.

The Great Lakes of North America and Europe’s many alpine lakes are examples of glacial lakes. 

Tectonic Lakes
tectonic lakes

When the Earth’s crust shifts, it causes changes in land elevation that result in the formation of basins, which in turn create tectonic lakes.

Lakes form when these depressions are flooded.

Tectonic lakes include bodies of water like Russia’s Lake Baikal and Africa’s Lake Tanganyika.

Fact: Lake Tanganyika is 1,436m deep, making it the second-deepest lake in the world. 
Volcanic Lakes

Lakes produced in the craters of now extinct or dormant volcanoes are known as volcanic lakes.

Crater lakes arise when rainwater or groundwater eventually fills the crater. Crater Lake in Oregon, USA, is an example of a volcanic lake. 

Erosion Lakes
erosion lakes

Erosion lakes are generated when water progressively erodes a basin into the surrounding landscape.

This can occur in coastal lakes due to coastal erosion or from the erosion of rivers and streams. 

Formation and Geological Features of Lagoons

formation and geological features of lagoons

A barrier like a sandbar, reef, or spit separates lagoons from deeper bodies of water like oceans and seas, making lagoons shallow bodies of water.

Riverine sediment deposition, coastal erosion, and fluctuating sea levels are just a few of the processes that might give rise to these features. 

Coastal lagoons

When sandbars or other barriers emerge along the coast, they trap water between themselves and the beach, creating a lagoon. 

Atoll Lagoons

Atoll lagoons form when coral reefs surround a volcanic island that has sunk below sea level, eventually producing a ring-shaped barrier that encloses a body of water.

As the volcanic island sinks, the coral reef rises, staying close to the water’s surface.

atoll lagoons

The Maldives and the Marshall Islands are both excellent examples of atolls with stunning lagoons. 

Riverine Lagoons

Riverine lagoons are generated when sediment is deposited by a riverbed, blocking off a segment of the river from the main flow.

Because of this, a lagoon may form on the river’s bank. The Camargue in southern France is a riverine lagoon.

Fact: The Indian River Lagoon in Florida, USA, and the Venice Lagoon in Italy are both examples of coastal lagoons. 

Size, Depth and Water Chemistry

size, depth and water chemistry

Both lagoons and lakes are different when you compare them based on their size, depth, and water chemistry.

It basically focuses on the key chemical and physical characteristics of these water bodies.

Here is more about it: 

Size and Depth of Lagoons and Lakes

Lagoons can be as little as solitary pools or as big as inland seas covering hundreds of square kilometers.

Depending on their location, lagoons can range from very shallow to very deep.    

On the other hand, lakes are mysterious bodies of water often encased in the land on all sides.

These mysterious pools of water come in a wide variety of sizes, from tiny ponds to enormous lakes like Lake Superior, which is more than 82,103 square kilometers in size.

Lakes also vary in terms of depth, with some offering only a few meters of water below the surface and others, like Lake Baikal, boasting a depth of more than 1,642 meters.   

Water Chemistry of Lagoons

water chemistry of lagoons

Lagoons’ proximity to, and shallowness in relation to, bigger bodies of water affects the chemistry of their water.

Because lagoons are frequently located near the sea or ocean, their water is frequently a hybrid of freshwater and salt.

Depending on how much freshwater is being added and how much evaporation is taking place, the salinity of lagoons can range from very fresh to extremely salty.

Organic matter and nutrients like nitrogen and phosphorus accumulate in lagoons in high concentrations.

Biological production can increase as a result of these nutrients, allowing for a rich and varied ecosystem to flourish.  

Fact: Lagoon water is typically brackish, meaning it has more salt than bottled water but less than ocean water. 

Water Chemistry of Lakes

water chemistry of lakes

The geology of the surrounding environment, temperature, and human activity all play a role in shaping the chemistry of lake water.

In contrast to lagoons, the salinity of freshwater lakes is typically below 0.5 parts per thousand.

Yet, evaporation and insufficient freshwater inflow can cause saline levels in some lakes to soar.

Lakes can range from being nutrient-poor and hence having low biological production to being nutrient-rich and therefore having high productivity.

The presence of acidic bedrock or atmospheric acid deposition can cause the lake water to be acidic.

But, the presence of limestone or other alkaline elements in the watershed can cause the lake water to be alkaline. 

Ecosystem and Biodiversity of Lakes and Lagoons

Although similar in appearance, lagoons and lakes really contain very different ecosystems and forms of biodiversity.

ecosystem and biodiversity of lakes and lagoons

The range of plant and animal life in these environments is affected by factors like:

  • Size
  • Depth
  • Water chemistry
  • Location

Let’s talk more about the similarities and differences between lagoons and lakes, focusing on their ecosystems and biodiversity. 


Lagoons are home to a diverse ecosystem thanks to the brackish conditions created when freshwater and saltwater mix.

There is a wide variety of fish, shellfish, birds, and aquatic plants that rely on lagoons for survival.

lagoons diverse ecosystem

Lagoons are home to a unique flora that includes macrophytes that float freely in the water, as well as emergent aquatic vegetation and marsh plants.

Many aquatic animals depend on these plants for survival because of the shelter and food they give.

Wading birds, shorebirds, and ducks are just a few of the many bird species that congregate in lagoons.

Moreover, lagoons play a crucial role in the lives of migrating bird species by providing critical resting and foraging areas along their long trips.

Fact: Juvenile fish and crustaceans rely heavily on lagoons for protection, food, and shelter. 


Factors such as water chemistry, depth, and the surrounding terrain all shape the biodiversity found in lakes.

Plant life in lakes is highly variable because of the varying nutrition and light conditions.

Plant life, both beneath and above water, flourishes in nutrient-rich, shallow lakes.

lakes formation

It is typically confined to the littoral zone in deeper, nutrient-poor lakes.

Large populations of fish species of commercial value can be found in some lakes, while other lakes are home to rare or endemic fish communities.

Many invertebrates are also found in lakes, such as:

  • Mollusks
  • Insects
  • Crustaceans

Bird species as varied as waterfowl, wading birds, and raptors thrive in lake ecosystems.

Some species of birds that are critically endangered or threatened rely on lakes as their only or principal breeding site


What’s the difference between lagoon and lake? While lakes and lagoons may look similar at first glance, important distinctions exist between them.

These differences are based on their formation, geological characteristics, size, depth, water chemistry, and biodiversity.

Lagoons and lakes have their own distinct qualities because of where they are, how they were formed, and the organisms they support, all of which contribute to the great diversity of watery habitats on Earth.