Lea Valley Walk

The Lea Valley Walk is a 50 miles (80 km) long-distance path located between Leagrave, the source of the River Lea near Luton, and the Thames, at Limehouse Basin, Limehouse, east London. From its source much of the walk is rural. At Hertford the path follows the towpath of the River Lee Navigation, and it becomes increasingly urbanised as it approaches London. The walk was opened in 1993 and is waymarked throughout using a swan logo.

More information on the Wikipedia page.