Like Lake Albano, the Lake of Nemi lies within a volcanic crater and shares its name with the largest town in the area directly overlooking the water. This sketch shows the view from the hill above the north-western shore looking towards the town of Nemi, recognisable by the circular medieval tower of the castle, Castello Ruspoli.
Turner has also made a smaller study in the bottom right-hand corner of the page which also appears to show Lake Nemi. The sketch spills over into the bottom left-hand corner of the opposite sheet see folio 20 (D15331), and is possibly a smaller version of the same view on that page.
For a general discussion of Turner’s view of Lake Nemi see folio 19 (D15329).