If you like scenic drives, the Edwin B Forsythe wildlife reserve down in Absecon/Galloway (right off Rt. 9) has a stunning 11?ish mile loop you can drive on. Bring binoculars and snacks and you can easily spend 2-3 hours driving around the loop. There are also some boardwalk areas. Nearby is Historic Smithville, which would be accessible to look around and take in the atmosphere, but most shops are not really accessible.

Cohanzick Zoo down in Bridgeton is accessible and free.

Cape May County Zoo is as well, plus it's a beautiful town to visit. Just do research first since many of the buildings are older and accessibility can be iffy.

If you like trails, there are numerous accessible ones in the Pine Barrens: http://www.accessnaturenj.org/