The world’s largest beaver dam, buried in the thick wildness of northern Alberta and once thought to be inaccessible, has been reached by an amateur explorer from the United States.

“The scope of it, you can just feel the immensity of it,” said Rob Mark, who travelled from New Jersey to become the first person to set foot on the structure.

The massive 850-metre long dam was first spotted on satellite photos in 2007. It was found in Wood Buffalo National Park, about 190 kilometres northeast of Fort McMurray.

A shot taken from on top of the massive dam. “I saw one beaver...he wasn't happy I was there either, he was slapping his tail on the water and wanted me out of there,” Mark said. (Rob Mark)

“There was a reoccurring theme that it was incredibly remote and thought to be inaccessible. Those two things sparked my interest and I started doing research,” he said.

Mark used a combination of Google Maps and topographical maps to mark out a route that he thought would take him to the dam. Then, after reading up on local wildlife and the terrain, he set off.

A boat took Mark from Fort Chipewyan to the edge of Lac Clair. From there, he hiked a route that few, if any, humans have ever travelled.

“It was ten miles to the dam. It was the longest, hardest ten miles I have ever travelled,” said Mark, who has hiked to remote areas in Peru and the Amazon rainforest.

“It is incredibly difficult country to get through. The foliage is so thick, you can’t see very far … then it turns into muskeg, which is incredibly difficult to walk on. And then it goes out to complete bog swamp.

“The mosquitoes are absolutely horrific.”

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Despite the untouched wilderness, Mark says he didn’t encounter any wildlife until he reached the dam and was confronted with a single, angry resident.

“I saw one beaver... he wasn't happy I was there either, he was slapping his tail on the water and wanted me out of there.”

Despite the difficult journey, Mark says the feeling when he finally stepped foot on the dam was well worth it.

“It felt like I just scored the winning goal in Game 7. I felt incredibly proud that I actually found it and made it there.

"And that I was able to document this and map it in such a way that future scientists, biologists and explorers can study this truly natural wonder.”