When? 40 years ago
Where? Get beyond Hyannis
How? Time Travel?

OK. I haven't been back in 25 years and frankly, I was disappointed. I spent 2-3 weeks on the Cape every summer of my childhood and it ain't what it once was. Nothin' you can do about that. However, do yourself a favor and get past the congestion of Hyannis. Orleans, Welfleet, Truro - there may still be unspoiled parts. The time to go is after Labor Day when the crowds abate because children return to school.

Still, if I had access to a time machine ....