When I'm at Acadia National Park, as I am right now, I make sure to visit to the southwestern edge of Mount Desert Island where migrating song and shorebirds stop before launching across Blue Hill Bay. This lighthouse marks the southern tip.
The Bass Harbor Head Light has warned sailors of the rocky entrance to Bass Harbor since 1858. It was automated in 1974 so there's no access inside, just a pretty walk down to the shore where the view of the lighthouse dominates the sky.
But don't take that walk in the fog. The path is rocky and steep.
You need fair weather to go to the lighthouse.
(photo from NOAA via Wikimedia Commons. Click on the photo to see the original)