Not on display
There are two drawings here, made with the page turned horizontally both ways. With the gutter at the bottom, the larger view shows the slender lighthouse (since replaced) overlooking the harbour channel, as seen on numerous adjacent pages, and other buildings including a nearby windmill. The other way up is a shore study with waves or dunes in the foreground, perhaps with one or two small, silhouetted figures.
See also Powell 1995, pp.72, 82 note 71, 246.