There are much more than black bears hidden among the vast old-growth forests and frosty-topped, towering mountains of the Great Smoky Mountains National Park. Although the more than half-million-acre park straddling the North Carolina-Tennessee border is the most-visited national park in the country, hosting 10 million visitors in 2014, its rugged wildness makes parts of the park still largely unexplored. The park is so biologically diverse, it is known to contain at least 100 species of trees, 1,500 plant species, 200 species of birds, 66 types of mammals, 67 native fish species and 39 varieties of reptiles, among many others being discovered all the time, and likewise more waterways. Because of its exceptionally high rainfall, the park is also home to plenty of streams, and after a three-year, stream-mapping project, scientists in the Smokies have discovered that the park contains about 900 more miles of streams than originally thought. As the study is ongoing, it’s expected there will be more streams discovered in the coming years.