The GORE-TEX North Face Endurance Challenge returns to Algonkian Regional Park, Great Falls Park and the Potomac Heritage Trail. The course keeps runners on their toes with ever-changing terrain. The course consists of mainly single and double track with a few spots of carriage road in the mix. Trail running distances available are 50 Mile, 50K, Marathon, Marathon Relay, Half Marathon, 10K and 5K.