D4 Impossible

D4 Impossible is one of the extreme one-way trails that climbs up the mountain from D1 Rubicon Ridge up to the main Arkansas-5 trail on the ridge. D4 begins with a slight descent on loose rock, but quickly turns uphill near the power lines. The grade is near vertical in many places, with a combination of loose rock and solid rock ledges. The park rating for this trail is a maximum 6 diamonds. A Park Day-Use Trail Pass is required to access this system of trails. Cell service is spotty in places, and trail conditions can change quickly, especially during rainy or winter seasons.