Wood Buffalo National Park is the largest National Park of Canada at 44,807 km2 (17,300 sq mi). It is located in northeastern Alberta and the southern Northwest Territories. Larger in area than Switzerland, it is the second-largest national park in the world. The park was established in 1922 to protect the world's largest herd of free roaming hybridized wood bison, currently estimated at more than 5,000.
The world's largest beaver dam – about 850-metre (2,790 ft) in length – was discovered in the park using satellite imagery; The dam, located at 58°16.3′N 112°15.1′W, about 200 kilometres (120 mi) from Fort Chipewyan.
The beavers in Canada’s Wood Buffalo National Park have been hard at work for decades, and their tree-chomping labor has paid off. The furry architects have created the largest beaver dam in the world.
The dam, which is about a half a mile long, is so massive it even shows up on satellite images. It remained hidden within the Alberta wilderness until 2007, when a researcher spotted it while looking at Google Earth.
Beavers are one of the few species capable of creating structures that are significant enough to be seen from space. The toothy critters are remarkable environmental engineers. Their dams reroute streams and even alter entire ecosystems. These creations, which are built to last, are barriers that form ponds, which act like defensive moats to protect them from predators like wolves and bears.
According to en.wikipedia