Northern Canada’s beavers used branches and mud to slow floodwaters; their 850-meter dam that can be seen from space transformed the forest into a pond holding 70 million liters of water over time

Deep inside Northern Alberta’s Wood Buffalo National Park, generations of beavers have constructed the largest known dam on Earth. Spanning 850 meters through remote wetlands, the massive structure holds roughly 70 million liters of water and is visible from satellite imagery in space. The animals began weaving branches, soil, and mud together in the 1970s to build a natural defense against local predators. Over decades, their persistent engineering transformed a simple forest channel into a thriving, nutrient-rich pond.