Northern River Otters

From Great Smoky Mountains National Park:

Now that the leaves are off the bushes and trees surrounding riverbanks, you may have a better chance of seeing northern river otters (Lontra canadensis) along Abrams Creek, Little River, or Fontana Lake. Otters are famous for their ability to make a game out of almost any activity. If you're lucky enough to be in the park after a snowstorm, keep an eye out for slide marks in the snow where these playful creatures have belly-surfed down a bank into a river. 

Photo by Warren Bielenberg.