The diocese in its full form included the Outer Hebrides, most of the Inner Hebrides (including Iona, Skye, Raasay, Canna, Eigg, Coll, Tiree, Mull, Colonsay, Islay, Jura, Gigha - but not Lismore, Kerrera, Seil or Luing, all under the Bishop of Argyll), the Isle of Bute and the Isle of Arran, as well as the Isle of Man (Mann). The diocese may have originally contained Galloway, a suggestion thought to explain the possible attacks of Wimund on Bishop Gilla Aldan of Whithorn.