Langness is a peninsula which protrudes nearly two kilometres from the south eastern extremity of the Isle of Man. Signifying a cape or extended promontory, Langness literally means long promontory in Old Norse. At one time an island, Langness was eventually joined to the mainland by the movement and deposition of material along Castletown Bay to form a tombolo. The small community of Derbyhaven is situated on this strip of land which lies close to Castletown, Isle of Man.
At the southern tip of the peninsula is Dreswick Point, the southeastern-most point of the Manx mainland, whilst St Michael's Isle (popularly known as Fort Island) is connected at the northern end of the peninsula by a narrow causeway.
The Castletown Golf & Country Club is set on the peninsula and the land connecting it with Derbyhaven.