The Diocese of the Isles, also known as the Diocese of Suðreyar, or the Diocese of Sodor, was one of the dioceses of medieval Norway. After the mid-13th-century Treaty of Perth, the diocese was accounted as one of the 13 dioceses of Scotland. The original seat of the bishopric appears to have been at Peel, on St Patrick's Isle, where indeed it continued to be under English overlordship; the Bishopric of the Isles as it was after the split was relocated to the north, firstly to Snizort and then Iona.