Stanely Castle is located in the waters of Stanely Reservoir, to the south of Paisley, Scotland, at the foot of the Gleniffer Braes. It was probably built in the early 15th century, on an island within a marsh. The castle is now a ruin. Since 1837 it has been partially submerged by the reservoir, and is completely inaccessible. When the water is drained it can be seen that the castle stands on a narrow promontory, which is connected to the reservoir bank on the southwest.