National Cycle Route 12 is part of the National Cycle Network managed by the charity Sustrans. It currently has a length of 121 miles (195 km) but is incomplete. When fully constructed it will run from Enfield Lock (London) to Grimsby (Lincolnshire) in the United Kingdom.

Enfield Lock is an area in the London Borough of Enfield, north London. It is approximately located east of the Hertford Road between Turkey Street and the Holmesdale Tunnel overpass, and extends to the River Lee Navigation, including the Enfield Island Village. The locality gains its name from the lock on the River Lee Navigation. Today's Enfield Lock was rebuilt in 1922. The area forms part of the Lee Valley Park and the Enfield Lock Conservation Area. On its eastern boundary Enfield Lock has marshland formerly used as a testing site between the Royal Small Arms Factory and the Gunpowder Mills, beyond this is the village of Sewardstone and the Epping forest boundary. To the south is Brimsdown, the north Waltham Cross and to the west Bullsmoor and Freezywater. Enfield Lock forms part of the London boundary.