My father and his friend visited the Atlantic Coast with his 8mm camera in Summer 1957. In this picture from his film clip (just after visiting Thunder Hole) there's this stone building with a wood deck on the left. Small boats come and go and there seem to be a lot of visitors.

There are floating docks and waterskiing in the area. Film content of this area starts here.

I'm trying to ID locations in his films and would appreciate any help! His grandson is making a similar Atlantic Coast trip and may try visiting the same areas.

If you're interested, the entire 8mm film is here. The Acadia National Park content starts 3 minutes into the film.