Delaware Water Gap National Recreation Area

The Delaware Water Gap is situated in the most densely populated region of the United States, straddling New Jersey and Pennsylvania. It runs along forty miles of the longest free-flowing river east of the Mississippi. One can camp there. here is decent hiking and a couple waterfalls. We hiked the Tammany Trail (red dot with a touch of the white dot Appalachian Trail) to the best possible vista and tubed down the river, both highly recommended. 

What is this? Spied a few weeks later plastered on a building in Belfast: