During the Backwoods Challenge, runners shimmy through a tunnel of mud, step across a balance beam, army-crawl under barbed wire, and shoot through a slide before plunging into a pond. And for some of them, there isn't even a prize on the line. In addition to frequent competitive races, Backwoods Challenge also hosts fun runs and mud-run training sessions. Either way, the 5K course, which pushes bodies and minds to the brink, forces participants to confront more than 25 obstacles that test their physical prowess. Only those who aren't afraid to get down and dirty in the mud can conquer all of the manmade and natural obstacles.