It joins the Peak Forest Canal on the eastern edge of Marple, at the top of a flight of 16 locks that raise the lower Peak Forest by to join the upper section. There was once a Stop Lock at Marple, although both canals were built to the same level, and the lock was provided only for cases where water shortages might have resulted in a temporary difference. The lock has long been de-gated, having become unnecessary once the Macclesfield and Peak Forest canals came into common ownership. The site of the lock remains as a narrows just in front of the junction bridge, and is overlooked by a canal warehouse with two storeys, built in 1835. It has a rectangular plan, and includes an internal waterway.