Fog at sunrise. C&O Canal NHP. January 25, 2019 at 1080 × 721 in C&O Canal National Historical Park, 2018 ← Previous Early one crisp, foggy morning at the Canal. Looking south toward Mather Gorge. From the first Olmsted Island footbridge looking south toward Mather Gorge. Early twilight is enhanced by the mist rising off the Potomac river.