Historically, a “landmark” is a conspicuous and recognizable object that guides and often pleases a traveler in the hard world, while a “seamark” is the same for travelers in the wet world, except it also often signals danger. In this context, consider Sun’s Up, the flashy little lobster boat with the big forward sheer:
She’s part of the wet world, but also something that many drivers on the hard world's Route 175 eagerly look for when they come to Conary Cove in Blue Hill. (Blue Hill, Maine; image taken May 22)