HoyHoy (from Old Norse há-øy meaning high island) is one of the Orkney Islands.
The dramatic coastline of Hoy is what usually greets visitors to the Orkney Islands. It has extremes of many kinds: some of the highest cliffs in Britain at St John's Head; the impressive and famous sea stack, the Old Man of Hoy; some of the most northerly woodland in Britain; the remote possiblity that Arctic Char survive in Heldale Water and the most northerly Martello Towers, which were never used in combat.
The main naval base for Scapa Flow in both the First and Second World Wars was situated at Lyness in the south-east of the island. Some rather incongruous art deco structures nearby date from this period.