Coeffin Castle was built in the 13th century, probably by the MacDougalls of Lorn. Lismore was an important site within their lordship, being the location of St. Moluag's Cathedral, seat of the Bishop of Argyll. The first written evidence of the castle occurs in 1469–70, when it was granted to Sir Colin Campbell of Glenorchy by Colin Campbell, 1st Earl of Argyll. It is unlikely to have been occupied in post-mediaeval times.A tidal fish trap, of unknown age, is located in the small bay to the south-east of the castle. To the north-east of the castle are the remains of a stone-walled fort. Castle Coeffin has been described as "a very ancient Scandinavian fortalice in Lismore and Appin parish, Argyllshire, on the NW side of Lismore island, 2.5 miles from the north-eastern extremity, now a dilapidated ivy-clad ruin.
Please note the geocache is not the castle.