The five interconnected Great Lakes—Huron, Ontario, Michigan, Erie, and Superior—form the largest system of fresh surface water on Earth. This massive system holds a significant portion of the planet’s liquid freshwater. When comparing the physical dimensions of these bodies of water, the largest Great Lake by surface area is Lake Superior.
Largest by Surface Area
Surface area is the most common metric used to define the size of a lake. Lake Superior is the largest of the five by this measurement, covering 31,700 square miles (82,100 square kilometers). This area makes it the largest freshwater lake in the world, comparable in size to the state of South Carolina.
Following Lake Superior in the ranking is Lake Huron, covering approximately 23,000 square miles. Lake Michigan is third with a surface area of about 22,300 square miles. Lake Erie and Lake Ontario follow, with surface areas of roughly 9,910 and 7,340 square miles, respectively. Lake Ontario is the smallest by this measure.
Comparing Volume and Depth
While Lake Superior dominates in surface area, it also holds the title for the largest volume of water and the greatest maximum depth. Its immense basin holds nearly 3,000 cubic miles of water, an amount greater than the combined volume of the other four Great Lakes plus three additional Lake Eries. This volume is directly related to its depth, which significantly exceeds the other lakes.
Lake Superior plunges to a maximum depth of 1,333 feet (406 meters), making it the deepest point in the system. The depths of the other lakes vary considerably, with Lake Michigan holding the second-largest volume at 1,180 cubic miles. Lake Erie is the shallowest of the five, reaching a maximum depth of 210 feet.
The Scope of the Great Lakes System
The collective scale of the five Great Lakes contains about 21% of the world’s surface freshwater. This volume of water is shared between the United States and Canada, with the international border passing through four of the five lakes. The system sustains the regional economy, providing drinking water for over 30 million people across both nations.
The lakes are a major corridor for commercial shipping, supporting the movement of iron ore, grain, and other bulk freight. Additionally, the extensive shorelines and diverse habitats support a vast and complex ecology. This shared international resource is a defining geographical and economic feature of North America.