Hey I just moved out of Delaware! Brandywine state park off of 141 in Wilmington is nice. Brandywine Creek Park is a shorter paved path mostly used for running but is nice. Alopocas is also a nice paved path. White Clay Creek park is nice, it is in Newark and runs into Penn. Fair Hill in Maryland is a nice park where they have some hiking trails off of 273 in Maryland. Bombay Hook is on the coast about halfway to Lewes from Wilmington, just outside of Smyrna, it has really great birdwatching. Other than that if you want real wilderness you need to leave the state. Pa, Md, Virginia, WV, NY, and of course the other Northeastern states have lots of opportunities as well. I visit the Adirondacks as much as possible.