This image shows a rock formation along the coastline of Bailey Island, Maine, which is given the colorful name of Pirate’s Cave.
The description states:
Bailey Island, Maine
–The cave is difficult to make out in this image, but is presumably the darkened area in the center. The rocky foreshore seems an unlikely place for a landing, and the label may be just a promotional effort by the makers of the postcard.
This image likely dates from the 1940s.