Great Lakes System

The Great Lakes system includes five major lakes—Superior, Huron, Michigan, Erie, and Ontario—along with Lake St. Clair and the connecting channels. There are also many harbours and bays spread throughout the region.
Each lake has its own unique features, circulation patterns, and ecosystems.

Together, the Great Lakes hold nearly 20 percent of the world’s fresh surface water.
In fact, 95 percent of North America’s fresh surface water is in these lakes.
Their combined coastline is longer than the entire East Coast of the United States.

And all of this water is connected—from the lakes to the ocean.

Here’s how it flows:
Water starts in Lake Superior and Lake Michigan, then moves to Lake Huron, through Lake St. Clair, into Lake Erie, over Niagara Falls, and finally into Lake Ontario.
From there, it flows through the St. Lawrence River, all the way to the Atlantic Ocean.

Rivers and streams carry nutrients, minerals, and sometimes even pollutants into the lakes from surrounding areas.

Now, let’s talk about location.

There are five Great Lakes, but only four of them—Superior, Huron, Erie, and Ontario—touch Canada.
They all lie within the province of Ontario.
Lake Michigan is the only one that’s entirely in the United States.

These lakes are so massive, they supply drinking water to millions of people.
They also support farming, industry, and tons of recreational activities like boating, swimming, and fishing.

But the Great Lakes do more than just hold water—they help shape the climate.

Because water heats and cools more slowly than land, the lakes act like natural temperature regulators.
In spring, they keep the air cooler.
In fall, they help hold on to heat, keeping the region warmer.
This delay in temperature changes helps farmers avoid early frosts.
In winter, cold air moving over the warmer lake water creates lake-effect snow—which often means heavy snowfall in nearby towns.

And don’t forget about shipping.

The Great Lakes are part of a huge transportation system.
Ships carry goods across the lakes and down the St. Lawrence Seaway, heading toward the Atlantic.
This route is sometimes called “Highway H2O”, and it plays a major role in the economy.

You might even hear people call the Great Lakes the “Sweetwater Seas.”
They’re so large that astronauts can see their shapes from space.

But to the people who live near them, these lakes are more than just water.
They shape daily life, weather, work, and tourism.
They bring beauty, opportunity, and a deep sense of connection to the land.

So next time you look at a map and spot those five lakes, remember—
They’re not just big.
They’re powerful.
They’re essential.
They’re one of Canada’s greatest natural treasures.

Now, let’s answer a few questions related to this topic.

Click anywhere on the flashcard to see the answer. To move to the next question, click on the small arrow at the bottom.