By Car:
From Boston area: Take Route 3 south, to the Sagamore Bridge in Bourne. Follow Route 6 eastward to Eastham and Provincetown. From Providence, RI: Take I-95 north to, I-195. Follow Route 6 eastward as described above.
Once on Cape, most park features are off Route 6 from Eastham to Provincetown. Stop at a park visitor center, or at a chamber of commerce, to get a map of the local vicinity.