There is a specific moment, somewhere out past Brant Point, when the island finally lets go of you.

It doesn’t happen at the dock. It doesn’t happen pulling away from Straight Wharf while tourists wave cocktails around on the upper deck and kids throw popcorn at gulls. For a while, Nantucket still hangs onto you. You can still see the church steeples over the rooftops. The masts in the harbor still stand upright against the sky. The shoreline remains detailed enough that you can pick out individual houses, and, for a few minutes, your mind keeps trying to convince itself that you’re still there.