The Northern Isles exclude Shetland.
 Shetland's most distinctive geological feature is the ultrabasic ophiolite, peridotite and gabbro on Unst and Fetlar, which are remnants of the Iapetus Ocean floor
 The Island of Stroma, which lies between mainland Scotland and Orkney, is part of Caithness, so for local government purposes it falls under the jurisdiction of the Highland council area, rather than that of Orkney

