Wood Buffalo National Park, in Canada, which spans northern Alberta and parts of the Northwest Territories, contains the largest beaver dam ever recorded. The structure lies deep within the park, far from roads, towns, or marked trails, making it largely inaccessible by foot. Its size is so vast that it is visible in satellite images taken from space. The dam measures roughly 775 metres along its front edge and covers an area of about 70,000 square metres, holding back a significant volume of water. It was first identified in 2007 through satellite imagery rather than ground exploration. Further analysis showed the dam did not exist before 1980, suggesting it was built over several decades by successive generations of beavers working in the same location.
A beaver dam hidden in Canada is clearly visible from space
Wood Buffalo National Park lies across northern Alberta and parts of the Northwest Territories. It is the largest national park in Canada and one of the largest protected areas in the world. The beaver dam sits deep within it, far from roads, towns, or marked trails.Reaching the site on foot would take days. The landscape is difficult and slow. Wetlands stretch for long distances. Muskeg gives way under weight. Boreal forest closes in thickly. Most people who have seen the dam up close did not walk there. They arrived by private sightseeing flights, looking down rather than approaching on the ground.
The actual size of the beaver dam is impressive
According to Parks Canada, from end to end, the front of the dam measures roughly 775 metres. That is close to seven football fields laid side by side. The entire perimeter of the dam area approaches 2,000 metres. Its surface area covers about 70,000 square metres.The pond created behind the dam is thought to be around one metre deep. That would place the volume of water at roughly 70,000 cubic metres. Another way to see it is through scale. A standard dump truck carries about 10 cubic yards. By that measure, the dam holds back the equivalent of more than 90,000 dump trucks of water. Seen as ice, it would fill around 1,600 hockey rinks.
This beaver dam was discovered from space
According to BBC Wildlife, no explorer stumbled across this dam by chance. No ranger logged it during patrol. It was first noticed in 2007, not on the ground, but in satellite imagery. The structure was large enough to be visible from space.Further images, including those provided by NASA, showed that the dam did not exist before 1980. That suggests it could be up to 45 years old. Over that time, it grew slowly, piece by piece, shaped by water flow and repeated work rather than a single effort. The location helped keep it hidden. With no nearby access routes, there was little reason for people to pass through.
Why beavers build on this scale
Beavers are often described as ecosystem engineers. They change landscapes by design, even if that design follows instinct rather than a plan. By felling trees and packing wood, mud, stones, and vegetation together, they redirect water and create ponds.In the case of this dam, multiple generations of beavers worked on the same structure. Each added material where it was needed. Over time, the dam expanded and strengthened, holding back runoff from the Birch Mountains at the southern edge of the park. The result is not just a barrier but an entire water system shaped by animals rather than machines.
What the dam means for the wider park
Wood Buffalo National Park is known for more than its size. It supports wood bison, whooping cranes, and the Peace Athabasca Delta, one of the largest inland freshwater deltas in the world. The beaver dam fits quietly into that setting.It supports wetlands, slows water movement, and creates habitat for other species. It does not draw crowds or require fences. It simply exists, doing its work out of sight. Even now, most people will never see it directly. The dam remains where it was built, surrounded by forest and water, changing its corner of the park a little at a time.