Dunyvaig Castle, also known as Dunnyveg, is a historic castle located on the south side of Islay in Scotland. It was once a naval base for the Lords of the Isles, chiefs of Clan Donald. The castle has a rich history dating back to the 12th century when it was built by Somerled, King of the Isles. Over the centuries, it changed hands between various clans and was eventually seized by the Covenanters in 1647. Today, all that remains are the ruins of this once-mighty fortress, including a courtyard from the 13th century and a keep from the 15th century.