Yellowstone is home to hundreds of species of birds, fish and mammals, according to the NPS. It is the only national park in North America where there are no fences to contain the wildlife, and therefore, they are able to roam freely, Hamilton said.

There’s a new milky blue pool in Yellowstone National Park.

Yellowstone National Park closed the Madison River, the Firehole River and the Gibbon River downstream of Norris Campground, as well as those rivers’ tributaries, on July 12. Fishing draws about 50,000 visitors to Yellowstone each year, according to the park’s website.