The World's Largest Beaver Dam Is Tucked Away In Canada's Largest National Park

Cathedrals, castles, and skyscrapers are architectural wonders we visit in modern cities, but nature has its own architects that have raised impressive structures in the Canadian wilderness. In northern Alberta, a colony of industrious beavers has constructed a dam that's visible from outer space. From end to end, the beaver dam is about 2,543 feet (almost a half mile) long, according to Parks Canada, making it the world's largest. If you laid the Empire State Building on its side without its spire and antenna, the dam would be over twice as long. The mammoth structure is in the wildlife-filled Wood Buffalo National Park, which also happens to be Canada's largest national park. Given that sheer space, the dam is not an easy sight to reach — it sits in the middle of the park, away from road or trail access. You're most likely to see it only by plane or helicopter.

In beaver real estate, building dams allows the animals to turn shallow streams into ponds and expand their territory. They live in the resulting ponds, serving as cover from predators and a place to store food. A dam as massive as the one at Wood Buffalo wasn't built by a single family of beavers, but rather is the result of multiple generations of beavers. Ecologist Jean Thie — who discovered the dam in 2007 while scouring satellite images — told The Independent that the dam has likely been under construction since the mid-1970s. It sits at the base of the Birch Mountains, where runoff comes down from higher ground and spreads across the flat terrain, per Canadian Geographic. That helps explain why the dam got so big: The beavers had to keep extending their dam sideways to keep water from trickling around its ends.

The world's largest beaver dam sits in the southern part of Wood Buffalo National Park, in a remote stretch of boreal forest, wetlands, and muskeg. Parks Canada gives visitors two options for reaching it: Trek for days through waterlogged terrain, or charter a private sightseeing plane. For most travelers, the flight is the only feasible choice. There's no dam parking lot, nor even a dam trailhead. A private bush plane or flight tour can take you over this isolated corner of the park, so you can see the dam's long profile aerially against the surrounding bog and forest.

Some operators serving the region offer custom backcountry charters that can be arranged on request. Phoenix Heli-Flight, for example, offers custom helicopter tours from Fort McMurray, south of the park, and holds five stars from Google Maps reviews. Another local operator, McMurray Aviation, also has strong reviews and offers customizable Cessna airplane tours over the boreal forest.

The alternative to chartering a flight is only for the most extreme, experienced explorers. Only one documented person is known to have reached the dam on foot: Rob Mark in 2014, according to Yale Environment 360. Mark spent years planning the expedition, and he reached the dam after a nine-day expedition. Visitors to Wood Buffalo National Park can stick to more attainable sights — the park is an under-the-radar Canadian destination for spotting wild roaming bison, which you can see from various roads. Or, you might consider a more accessible Alberta park to explore; Elk Island National Park is one outside Edmonton with more bison and trails.