What percentage of the world’s surface fresh water is held by the Great Lakes?

The Great Lakes hold about 21 percent of the world’s surface fresh water.

Together, Superior, Michigan, Huron, Erie, and Ontario contain roughly 22,700 cubic kilometres of water. Their enormous volume makes the system one of the planet’s most important freshwater resources, even though the lakes occupy a relatively small part of Earth’s land surface.

The commonly quoted figure refers to surface fresh water, not all water on Earth. Most of Earth’s freshwater is locked in glaciers and ice sheets or stored underground, so the Great Lakes represent a much smaller share of total global freshwater.

The lakes are also a connected system. Water flows generally from Lake Superior through the lower lakes and eventually reaches the Atlantic Ocean through the Saint Lawrence River. Their water supports drinking supplies, shipping, fisheries, recreation, industry, and wildlife across Canada and the United States.