I-80 enters Hardwick Township, Warren County from Pennsylvania on the Delaware Water Gap Toll Bridge over the Delaware River, maintained by the Delaware River Joint Toll Bridge Commission (DRJTBC). In addition to carrying I-80, this bridge also carries the Appalachian Trail over the Delaware River. From this point, the four-lane freeway heads south along the east bank of the river through the Delaware Water Gap, immediately reaching a westbound exit and eastbound entrance for Old Mine Road. Now maintained by NJDOT, the road makes a sharp turn to the east and comes to a U-turn ramp in both directions that also has access to the Appalachian Trail. NJDOT has proposed a controversial rock wall along the stretch to handle rock slides. The highway heads south again and enters Knowlton Township, where it comes to another set of U-turn ramps that also includes a weigh station in the eastbound direction. After turning southeast and leaving the Delaware Water Gap, the road has a westbound right-in/right-out for Hainesburg Road before crossing under the abandoned Lackawanna Cutoff. I-80 widens to six lanes and reaches a complex interchange with the western terminus of US 46, Route 94, and Decatur Street in Columbia, where development near the route increases. After this interchange, the freeway turns east away from the Delaware River and crosses over Paulins Kill before it continues through wooded and hilly areas containing some farms, with the eastbound direction widening from three to four lanes and the highway median also widens. A scenic overlook of the Delaware Water Gap is located in the westbound direction while a rest area is located in the eastbound direction.