Muckle Green Holm is an uninhabited island in the North Isles of the Orkney archipelago in Scotland. It is roughly 28 hectares (0.11 sq mi) in extent and rises to 28 metres above sea level, the summit having a trig point. The literal meaning of the name is somewhat contradictory. 'Holm' is from the Old Norse holmr, meaning a small and rounded islet. 'Muckle' is Scots for 'big' or 'large' so it's a big small island. To the south lies Little Green Holm, and between the two is the Sound of Green Holms. Eastward is a strait called Fall of Warness between Muckle Green Holm and the much larger island of Eday. In these waters the European Marine Energy Centre have installed tidal power testing equipment.