Chuck-- I got it! Don't know why I didn't think to use google... It's Newfound Lake, with East Hebron at the north end just visible in the left of the photo ahead of the wing. Note power lines which cross in front of the aircraft, which run roughly N-S on the west side of Newfound, two islands at the "bottom" of a hand-shaped lake. We were on our way back to Nashua, headed directly toward New Hampton, which is just out of the picture on the right. Thanks, mystery solved!