You’ve probably seen a lake before, or maybe even been swimming in a lake a few times.

But did you ever wonder how the lake got there?

Or what makes a lake different from other bodies of water? Keep reading to learn all that and more!

What is a lake?

A lake is a body of water that is surrounded by land and doesn’t move much. Lakes can be big or small, and they form inside of basins, which are basically bowl-shaped craters or holes in the ground.

Usually, rivers or streams flow into the lake and also drain water out of the lake when it gets too full. Sometimes water is drained from lakes only through evaporation, and these are called closed lakes.

Most lakes are freshwater, but some are saltwater. Closed lakes are usually saltwater, because water leaves behind salt as it evaporates.

Did you know that there are millions of lakes in the world? That’s a lot! There are lakes on all seven continents, and they can be found in all kinds of climates and environments.

How can you tell a lake apart from other bodies of water?

Although there is no official scientific measurement to separate lakes from ponds, lakes are generally larger and deeper. Lagoons connect to the ocean, and lakes do not. Rivers and streams flow and move constantly, and lakes hardly move at all.

How do lakes form?

There are several different ways a lake can form, but they all involve water finding its way into a basin.

Some lakes were formed by glaciers that scraped along the ground, forming giant basins as they moved along. When the glaciers eventually melted, the basins were filled with water, and lakes were made!

Other lakes form because of the movements of Earth’s tectonic plates. Sometimes plate movements break the Earth’s crust, causing big cracks that form basins. Over time, the basins fill with water from rain or from streams that flow into the basin.

Lakes are even formed by volcanoes. When a volcano becomes inactive, meaning it doesn’t erupt anymore, the crater in the top of the volcano can fill with melted snow or rainwater. Then you have a lake!


Another way volcanoes can form lakes is when the top of the volcano is blown off or collapses during an eruption. This makes a hole called a caldera, which can also fill with water and become a lake.

Another way lakes form is when landslides or mudslides cause rocks, dirt, or mud to pile up and block the flow of a river or stream.

Some lakes are man-made, either by digging basins or by blocking the flow of rivers or streams. These man-made lakes are called reservoirs. Reservoirs are often made to be used as sources of hydroelectric power, which can provide electricity to homes and businesses.

Facts about Lakes

-Not including oceans, lakes contain about 90% of all the water on Earth’s surface.

-Have you ever heard of the Loch Ness monster? It’s a (probably fictional) monster who lives in a lake, so why isn’t it called the Lake Ness monster instead? That’s because in Scotland, the home of the Loch Ness monster, lakes are referred to as lochs!

-The biggest lake in the world is the Caspian Sea, which is in Europe and Asia. It has an area of more than 143,000 square miles (370,000 square kilometers)!

-The largest saltwater lake in the United States is Utah’s Great Salt Lake. It is even saltier than the ocean.


-All lakes slowly disappear as the basins fill with plant material, dirt, sand, and bits of rock over time.

-Dry lake beds are awesome places to hunt for fossils!

-People who study lakes, rivers, and other inland water are called limnologists. The study of inland water is called limnology.

-Many lakes are home to diverse and rare plant and animal species.

-Lakes are used by people for drinking water, to water plants, to provide electricity, and for recreational activities like swimming, boating, and fishing.

-There are over 187,000 lakes in the country of Finland alone.

Now you know all about lakes. Next time you see a lake, you can amaze your family and friends with all of your new lake knowledge!