Scapa Flow contains several good anchorages, the best being Longhope in the island of Hoy.
The highest hills are found in Hoy.
The very names of the islands indicate their nature, for the terminal a or ay is the Norse ey, meaning "island," which is scarcely disguised even in the words Pomona and Hoy.
The upper division of the Old Red Sandstone is found only in Hoy, where it forms the Old Man and neighbouring cliffs on the N.W.
Near Haco's Ness in Shapinsay there is a small exposure of amygdaloidal diabase which is of course older than that in Hoy.
