The starting pistol fires and the runners are off, but they're in for a surprise. Rather than running an easy 5K around gentle bends and smooth pavement, they have to clamber over parked cars, carry hefty tires, and participate in burlap sack races before they even get near the finish line. This is the Waterfront Challenge, an urban race designed to test a runner's mettle, strength, and endurance on a route that runs through Louisville's scenic, 85-acre Waterfront Park along the Ohio River. The excitement extends beyond the unorthodox obstacles with waves that run late into the night—those who take off at 9 p.m. make up the Glow Race, which elevates the fun by illuminating runners with glow sticks, glow-in-the dark costumes, and the runners' own sweat, which is naturally bioluminescent. At the end of the race, runners celebrate their victories on Big Four Lawn where music, cold beer, and food join an awards ceremony for top finishers and best glow-in-the-dark costume.