That was my parents’ (and the whole family’s) favorite place of all the fabulous places in Maine when I was growing up. We anchored there many a night during the 1960s and 1970s (and I’m sure my folks did a few more times after that up until Dad died in 1993).
Back then it must have had quite a primal feeling. There still are virtually no structures visible from the water but it's different anyway. I went further up than I've done since there was a similar size boat still ahead. There is a 2' spot right in middle of narrow channel.
I'm thinking your parents lived in PA, kept a power boat in MA? Maine Islands do call to many a soul.