Dubh Artach (St. John's Rock) (56°08'N., 6°38'W.), a rocky islet fringed by reefs, lies 16 miles W of the N extremity of Colonsay. A light is shown from a tower on the islet. Above and below water rocks lie as far as 0.3 mile from the islet and there are several detached banks in the area around Dubh Artach.

Location