The Lee Navigation is a canalised river incorporating the River Lea (also called the River Lee). It runs from Hertford Castle Weir to the River Thames at Bow Creek. Much of the Lee Navigation is within Lea Valley Park. The Lea Valley Walk, a 50-mile long-distance public walking path and bicycle trail from the headwaters to the Thames confluence, follows the canal towpaths in the Lee Navigation section. Link Canal and River Trust Link Wikipedia