Castle Coeffin is located on the Isle of Lismore and is believed to have been built on the site of an earlier Viking fortress sometime during the 13th Century - probably by the MacDougalls. At the time, Lismore was a place of importance, being home to St. Moluag's Cathedral, seat of the Bishop of Argyll. The cathedral is believed to have been built during the late 12th or early 13th Century, making it likely that it pre-dated the castle.

Scant written reference to Castle Coeffin exists, but it is recorded that the Early of Argyll granted it to Sir Colin Campbell of Glenorchy. It is known to have remained in the possession of the Campbell family until the late 18th Century, but it is unlikely to have remained occupied up until such a late date.

Little remains of Castle Coeffin today. The castle sits atop a rocky crag, with only the skeletal ruin of a hall-house and bailey still standing. From a distance, it looks quite impressive, and it's surprising to discover how little there is to see when you get up close. Nevertheless, it's an incredibly beautiful location with some stunning views. The Isle of Lismore is a wonderful little bubble of seclusion not easily accessed from the mainland. The castle itself punches above its weight, with lots of atmosphere and character.