Observe if you will the mouth to a tunnel, circled in red in the picture, and seen in the enlarged section, which has been bored into the cliff. Is this a link leading into the countryside? A possible way of escape, like the tunnel in ‘Fall Out?’ Or is it more likely a boathouse built into the cliff, where the motor cruiser M.S. Polotska is moored when not in use? If it is, I can see one huge disadvantage to that, when the tide is out, and at certain times of the year that could have lasted for days on end, so the crew of the motor cruiser would find it impossible to put to sea!
Be seeing you