The borough of Delaware Water Gap is located at the southern end of the Recreation Area, and both the town and the park take their name from the geographical feature, the point where the Delaware River cuts through the Appalachian Mountains.

The Delaware Water Gap is a distinct geological feature where the Delaware River "cuts" through a large ridge of the Appalachian Mountains on the border of New Jersey and Pennsylvania. It is called a "gap" because it is a physical break in the otherwise continuous Kittatinny Ridge (in NJ) and Blue Mountain (in PA). Geologists believe the river was actually there before the mountains were fully formed; as the earth's crust folded and pushed the mountains upward millions of years ago, the river maintained its course by eroding the rock faster than the mountains could rise. This created a dramatic, steep-walled pass that stands roughly 1,200 feet deep. Historically, this gap was the only natural path through the rugged mountain range, making it a critical route for Native American trails, early settlers, railroads, and eventually Interstate 80. Today, it is a protected National Recreation Area famous for its hiking, rafting, and stunning vistas.