Discover the Deepest River in Canada

Written by Kyle Glatz
Updated: August 6, 2023
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Key Points

  • At a depth of between 318 feet, the Ottawa River is the deepest in Canada.
  • The Ottawa River begins at Ottawa Lake (Lac des Outaouais) and ends at the St. Lawrence River.  
  • The river flows for a total length of about 790 miles through the provinces of Quebec and Ontario.

Canada is known for having some of the longest rivers in North America. Additionally, the St. Lawrence River is one of the deepest rivers in the country. At 250 feet deep, it’s deeper than both the Hudson River and the Mississippi River. However, the St. Lawrence River is not the deepest one found in Canada. Discover the deepest river in Canada and learn where it is located, how deep it goes, and more!

What is the Deepest River in Canada?

The Ottawa River surrounded with trees under the cloudy sky in Ontario, Canada

The Ottawa River forms the border between Ontario and Quebec.

©Light and Vision/

The deepest river in Canada is the Ottawa River with a maximum depth of 318 feet. The river reaches this great depth between Chute-a-Blondeau and Greece’s Point, a little over a mile upriver of the Carillion Hydroelectric Facility. This location is on the river between Ottawa and Montreal, but it is closer to Montreal.  

Several other deeper measures exist for this river. One source states that the Ottawa River at Moose Bay reaches 565 feet deep. Another source claims that the river near the town of Deep River reaches over 400 feet deep. However, nautical charts for those regions show waters actually measure a little over 200 feet deep. While the depth of a river channel can change over time, it is hard to imagine they would get over 200 feet deeper without significant changes in the area.

Even at a depth of 318 feet, the Ottawa River is still the deepest in Canada by a wide margin. The next-deepest river is the St. Lawrence River with a depth of about 250 feet. Meanwhile, the longest river in Canada is the Yukon River which measures 1,982 miles long.  

Where is the Ottawa River Located on a Map?

The source of the Ottawa River is located at Ottawa Lake (Lac des Outaouais). The river flows west at first before turning south and becoming the dividing line between the provinces of Ontario and Quebec for the rest of its flow. The river flows through the city of Ottawa and continues east for several miles until it reaches Montreal.

Near that city, it reaches its mouth at the Lake of Two Mountains and the St. Lawrence River. From there, the St. Lawrence River continues to flow to the northeast, eventually emptying into the Atlantic Ocean.

Finding the river on a map is not very difficult since it forms a border between two provinces and runs through or near two well-known cities.  

Animals That Live in the Ottawa River

The Alexandra BridgeCantilever bridge in Ottawa, Canada

Many animals live in and alongside the Ottawa River.

©Photo Hedge/

A huge number of animals live in and near the deepest river in Canada. Some of the animals that live in and near the river and its associated wetlands include:

  • Spotted turtle
  • Common map turtle
  • Walleye
  • Muskellunge
  • Yellow perch
  • Smallmouth Bass
  • American eel
  • Longnose gar
  • Northern pike
  • Eastern ribbon snake
  • Northern water snake

The Ottawa River has a vast number of fish, amphibian, and reptile species all living in a delicate balance. Aside from the animals that are thriving in the river’s deep waters, even more of them are living in the immediate area around the river. The following animals and many others thrive along the banks of the river as it winds through Canada:

This is just a handful of the total number of animals that live along the banks of the Ottawa River. Many other species are found along the river’s 790-mile length including endangered species.  

Historical Significance of the Ottawa River

Lumberjack with modern harvester working in a forest. Wood as a source renewable energy.

The lumber industry has used the Ottawa River for transport in recent centuries.


The Ottawa River has a long history with the Algonquin people. In fact, archaeological data suggests that the Algonquin people have lived in the Ottawa Valley for the last 8,000 years. The arrival of the Europeans led by Samuel de Champlain eventually resulted in a fur trade between the French and the Algonquins in 1603.

Following that early contact, Samuel de Champlain established a settlement on the St. Lawrence River, left for Europe, returned to the area, and explored farther up the Ottawa River.

The river was a significant trade artery for Europeans from then on. Parts of the river would become an important part of the lumber industry as time went on, and eventually the site of several hydroelectric power stations. Today, the river is still significant to the Algonquin people, and they continue their land claim against the Canadian government.  

How Does the Deepest River in Canada Compare to the Deepest in the World?

Congo River

The Congo River is the deepest in the world!

© Salmon

The Ottawa River may have the greatest depth of any river in North America. So, how does it measure up on the world stage? Take a look at some of the deepest rivers in the world and how the Ottawa River compares.

River and LocationDepth
Ottawa River, North America318 feet
Congo River, Africa720 feet
Yangtze River, Asia650 feet
Danube River, Europe584 feet
Zambezi River, Africa381 feet

While the Ottawa River is deep, it would be the sixth-deepest river in the world, just ahead of the Mekong River. Of course, future nautical charts that plot the depth of the river could alter the placement of the river on the list. Several deep rivers measure between 300 and 350 feet.

The deepest river in Canada is often overlooked for its incredible depth. Part of the reason is that so many measures exist for it these days. Some sources claim that it is over 500 feet deep, making it one of the deepest in the world. However, nautical maps show that the river achieves a depth of about 318 feet just west of the Carillion Hydroelectric Facility.

The photo featured at the top of this post is © DD Images/

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About the Author

Kyle Glatz is a writer at A-Z-Animals where his primary focus is on geography and mammals. Kyle has been writing for researching and writing about animals and numerous other topics for 10 years, and he holds a Bachelor's Degree in English and Education from Rowan University. A resident of New Jersey, Kyle enjoys reading, writing, and playing video games.

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